# 2451 Agent Sdk Typescript C7cd0e66

> Installation

- Skill: `tools-only/2451-agent-sdk-typescript-c7cd0e66` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add tools-only/2451-agent-sdk-typescript-c7cd0e66`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tools-only/2451-agent-sdk-typescript-c7cd0e66/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: tools-only (https://skillmd.com/u/tools-only)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/tools-only/2451-agent-sdk-typescript-c7cd0e66

---


## Installation

    npm install @anthropic-ai/claude-agent-sdk

## Functions

### `query()`

The primary function for interacting with Claude Code. Creates an async generator that streams messages as they arrive.

    function query({
      prompt,
      options
    }: {
      prompt: string | AsyncIterable<SDKUserMessage>;
      options?: Options;
    }): Query

#### Parameters

| Parameter | Type | Description |
|----|----|----|
| `prompt` | `string | AsyncIterable<`[`SDKUserMessage`](https://platform.claude.com/docs/en/agent-sdk/typescript#sdkusermessage)`>` | The input prompt as a string or async iterable for streaming mode |
| `options` | [`Options`](https://platform.claude.com/docs/en/agent-sdk/typescript#options) | Optional configuration object (see Options type below) |

#### Returns

Returns a [`Query`](https://platform.claude.com/docs/en/agent-sdk/typescript#query-1) object that extends `AsyncGenerator<`[`SDKMessage`](https://platform.claude.com/docs/en/agent-sdk/typescript#sdkmessage)`, void>` with additional methods.

### `tool()`

Creates a type-safe MCP tool definition for use with SDK MCP servers.

    function tool<Schema extends ZodRawShape>(
      name: string,
      description: string,
      inputSchema: Schema,
      handler: (args: z.infer<ZodObject<Schema>>, extra: unknown) => Promise<CallToolResult>
    ): SdkMcpToolDefinition<Schema>

#### Parameters

| Parameter | Type | Description |
|----|----|----|
| `name` | `string` | The name of the tool |
| `description` | `string` | A description of what the tool does |
| `inputSchema` | `Schema extends ZodRawShape` | Zod schema defining the tool's input parameters |
| `handler` | `(args, extra) => Promise<`[`CallToolResult`](https://platform.claude.com/docs/en/agent-sdk/typescript#calltoolresult)`>` | Async function that executes the tool logic |

### `createSdkMcpServer()`

Creates an MCP server instance that runs in the same process as your application.

    function createSdkMcpServer(options: {
      name: string;
      version?: string;
      tools?: Array<SdkMcpToolDefinition<any>>;
    }): McpSdkServerConfigWithInstance

#### Parameters

| Parameter | Type | Description |
|----|----|----|
| `options.name` | `string` | The name of the MCP server |
| `options.version` | `string` | Optional version string |
| `options.tools` | `Array<SdkMcpToolDefinition>` | Array of tool definitions created with [`tool()`](https://platform.claude.com/docs/en/agent-sdk/typescript#tool) |

## Types

### `Options`

Configuration object for the `query()` function.

| Property | Type | Default | Description |
|----|----|----|----|
| `abortController` | `AbortController` | `new AbortController()` | Controller for cancelling operations |
| `additionalDirectories` | `string[]` | `[]` | Additional directories Claude can access |
| `agents` | `Record<string, [`AgentDefinition`](#agentdefinition)>` | `undefined` | Programmatically define subagents |
| `allowedTools` | `string[]` | All tools | List of allowed tool names |
| `canUseTool` | [`CanUseTool`](https://platform.claude.com/docs/en/agent-sdk/typescript#canusetool) | `undefined` | Custom permission function for tool usage |
| `continue` | `boolean` | `false` | Continue the most recent conversation |
| `cwd` | `string` | `process.cwd()` | Current working directory |
| `disallowedTools` | `string[]` | `[]` | List of disallowed tool names |
| `env` | `Dict<string>` | `process.env` | Environment variables |
| `executable` | `'bun' | 'deno' | 'node'` | Auto-detected | JavaScript runtime to use |
| `executableArgs` | `string[]` | `[]` | Arguments to pass to the executable |
| `extraArgs` | `Record<string, string | null>` | `{}` | Additional arguments |
| `fallbackModel` | `string` | `undefined` | Model to use if primary fails |
| `forkSession` | `boolean` | `false` | When resuming with `resume`, fork to a new session ID instead of continuing the original session |
| `hooks` | `Partial<Record<`[`HookEvent`](https://platform.claude.com/docs/en/agent-sdk/typescript#hookevent)`,`[`HookCallbackMatcher`](https://platform.claude.com/docs/en/agent-sdk/typescript#hookcallbackmatcher)`[]>>` | `{}` | Hook callbacks for events |
| `includePartialMessages` | `boolean` | `false` | Include partial message events |
| `maxThinkingTokens` | `number` | `undefined` | Maximum tokens for thinking process |
| `maxTurns` | `number` | `undefined` | Maximum conversation turns |
| `mcpServers` | `Record<string, [`McpServerConfig`](#mcpserverconfig)>` | `{}` | MCP server configurations |
| `model` | `string` | Default from CLI | Claude model to use |
| `outputFormat` | `{ type: 'json_schema', schema: JSONSchema }` | `undefined` | Define output format for agent results. See [Structured outputs](https://platform.claude.com/docs/en/agent-sdk/structured-outputs) for details |
| `pathToClaudeCodeExecutable` | `string` | Auto-detected | Path to Claude Code executable |
| `permissionMode` | [`PermissionMode`](https://platform.claude.com/docs/en/agent-sdk/typescript#permissionmode) | `'default'` | Permission mode for the session |
| `permissionPromptToolName` | `string` | `undefined` | MCP tool name for permission prompts |
| `plugins` | [`SdkPluginConfig`](https://platform.claude.com/docs/en/agent-sdk/typescript#sdkpluginconfig)`[]` | `[]` | Load custom plugins from local paths. See [Plugins](https://platform.claude.com/docs/en/agent-sdk/plugins) for details |
| `resume` | `string` | `undefined` | Session ID to resume |
| `settingSources` | [`SettingSource`](https://platform.claude.com/docs/en/agent-sdk/typescript#settingsource)`[]` | `[]` (no settings) | Control which filesystem settings to load. When omitted, no settings are loaded. **Note:** Must include `'project'` to load CLAUDE.md files |
| `stderr` | `(data: string) => void` | `undefined` | Callback for stderr output |
| `strictMcpConfig` | `boolean` | `false` | Enforce strict MCP validation |
| `systemPrompt` | `string | { type: 'preset'; preset: 'claude_code'; append?: string }` | `undefined` (empty prompt) | System prompt configuration. Pass a string for custom prompt, or `{ type: 'preset', preset: 'claude_code' }` to use Claude Code's system prompt. When using the preset object form, add `append` to extend the system prompt with additional instructions |

### `Query`

Interface returned by the `query()` function.

    interface Query extends AsyncGenerator<SDKMessage, void> {
      interrupt(): Promise<void>;
      setPermissionMode(mode: PermissionMode): Promise<void>;
    }

#### Methods

| Method | Description |
|----|----|
| `interrupt()` | Interrupts the query (only available in streaming input mode) |
| `setPermissionMode()` | Changes the permission mode (only available in streaming input mode) |

### `AgentDefinition`

Configuration for a subagent defined programmatically.

    type AgentDefinition = {
      description: string;
      tools?: string[];
      prompt: string;
      model?: 'sonnet' | 'opus' | 'haiku' | 'inherit';
    }

| Field | Required | Description |
|----|----|----|
| `description` | Yes | Natural language description of when to use this agent |
| `tools` | No | Array of allowed tool names. If omitted, inherits all tools |
| `prompt` | Yes | The agent's system prompt |
| `model` | No | Model override for this agent. If omitted, uses the main model |

### `SettingSource`

Controls which filesystem-based configuration sources the SDK loads settings from.

    type SettingSource = 'user' | 'project' | 'local';

| Value | Description | Location |
|----|----|----|
| `'user'` | Global user settings | `~/.claude/settings.json` |
| `'project'` | Shared project settings (version controlled) | `.claude/settings.json` |
| `'local'` | Local project settings (gitignored) | `.claude/settings.local.json` |

#### Default behavior

When `settingSources` is **omitted** or **undefined**, the SDK does **not** load any filesystem settings. This provides isolation for SDK applications.

#### Why use settingSources?

**Load all filesystem settings (legacy behavior):**

    // Load all settings like SDK v0.0.x did
    const result = query({
      prompt: "Analyze this code",
      options: {
        settingSources: ['user', 'project', 'local']  // Load all settings
      }
    });

**Load only specific setting sources:**

    // Load only project settings, ignore user and local
    const result = query({
      prompt: "Run CI checks",
      options: {
        settingSources: ['project']  // Only .claude/settings.json
      }
    });

**Testing and CI environments:**

    // Ensure consistent behavior in CI by excluding local settings
    const result = query({
      prompt: "Run tests",
      options: {
        settingSources: ['project'],  // Only team-shared settings
        permissionMode: 'bypassPermissions'
      }
    });

**SDK-only applications:**

    // Define everything programmatically (default behavior)
    // No filesystem dependencies - settingSources defaults to []
    const result = query({
      prompt: "Review this PR",
      options: {
        // settingSources: [] is the default, no need to specify
        agents: { /* ... */ },
        mcpServers: { /* ... */ },
        allowedTools: ['Read', 'Grep', 'Glob']
      }
    });

**Loading CLAUDE.md project instructions:**

    // Load project settings to include CLAUDE.md files
    const result = query({
      prompt: "Add a new feature following project conventions",
      options: {
        systemPrompt: {
          type: 'preset',
          preset: 'claude_code'  // Required to use CLAUDE.md
        },
        settingSources: ['project'],  // Loads CLAUDE.md from project directory
        allowedTools: ['Read', 'Write', 'Edit']
      }
    });

#### Settings precedence

When multiple sources are loaded, settings are merged with this precedence (highest to lowest):

1. Local settings (`.claude/settings.local.json`)
2. Project settings (`.claude/settings.json`)
3. User settings (`~/.claude/settings.json`)

Programmatic options (like `agents`, `allowedTools`) always override filesystem settings.

### `PermissionMode`

    type PermissionMode =
      | 'default'           // Standard permission behavior
      | 'acceptEdits'       // Auto-accept file edits
      | 'bypassPermissions' // Bypass all permission checks
      | 'plan'              // Planning mode - no execution

### `CanUseTool`

Custom permission function type for controlling tool usage.

    type CanUseTool = (
      toolName: string,
      input: ToolInput,
      options: {
        signal: AbortSignal;
        suggestions?: PermissionUpdate[];
      }
    ) => Promise<PermissionResult>;

### `PermissionResult`

Result of a permission check.

    type PermissionResult = 
      | {
          behavior: 'allow';
          updatedInput: ToolInput;
          updatedPermissions?: PermissionUpdate[];
        }
      | {
          behavior: 'deny';
          message: string;
          interrupt?: boolean;
        }

### `McpServerConfig`

Configuration for MCP servers.

    type McpServerConfig = 
      | McpStdioServerConfig
      | McpSSEServerConfig
      | McpHttpServerConfig
      | McpSdkServerConfigWithInstance;

#### `McpStdioServerConfig`

    type McpStdioServerConfig = {
      type?: 'stdio';
      command: string;
      args?: string[];
      env?: Record<string, string>;
    }

#### `McpSSEServerConfig`

    type McpSSEServerConfig = {
      type: 'sse';
      url: string;
      headers?: Record<string, string>;
    }

#### `McpHttpServerConfig`

    type McpHttpServerConfig = {
      type: 'http';
      url: string;
      headers?: Record<string, string>;
    }

#### `McpSdkServerConfigWithInstance`

    type McpSdkServerConfigWithInstance = {
      type: 'sdk';
      name: string;
      instance: McpServer;
    }

### `SdkPluginConfig`

Configuration for loading plugins in the SDK.

    type SdkPluginConfig = {
      type: 'local';
      path: string;
    }

| Field | Type | Description |
|----|----|----|
| `type` | `'local'` | Must be `'local'` (only local plugins currently supported) |
| `path` | `string` | Absolute or relative path to the plugin directory |

**Example:**

    plugins: [
      { type: 'local', path: './my-plugin' },
      { type: 'local', path: '/absolute/path/to/plugin' }
    ]

For complete information on creating and using plugins, see [Plugins](https://platform.claude.com/docs/en/agent-sdk/plugins).

## Message Types

### `SDKMessage`

Union type of all possible messages returned by the query.

    type SDKMessage = 
      | SDKAssistantMessage
      | SDKUserMessage
      | SDKUserMessageReplay
      | SDKResultMessage
      | SDKSystemMessage
      | SDKPartialAssistantMessage
      | SDKCompactBoundaryMessage;

### `SDKAssistantMessage`

Assistant response message.

    type SDKAssistantMessage = {
      type: 'assistant';
      uuid: UUID;
      session_id: string;
      message: APIAssistantMessage; // From Anthropic SDK
      parent_tool_use_id: string | null;
    }

### `SDKUserMessage`

User input message.

    type SDKUserMessage = {
      type: 'user';
      uuid?: UUID;
      session_id: string;
      message: APIUserMessage; // From Anthropic SDK
      parent_tool_use_id: string | null;
    }

### `SDKUserMessageReplay`

Replayed user message with required UUID.

    type SDKUserMessageReplay = {
      type: 'user';
      uuid: UUID;
      session_id: string;
      message: APIUserMessage;
      parent_tool_use_id: string | null;
    }

### `SDKResultMessage`

Final result message.

    type SDKResultMessage = 
      | {
          type: 'result';
          subtype: 'success';
          uuid: UUID;
          session_id: string;
          duration_ms: number;
          duration_api_ms: number;
          is_error: boolean;
          num_turns: number;
          result: string;
          total_cost_usd: number;
          usage: NonNullableUsage;
          permission_denials: SDKPermissionDenial[];
        }
      | {
          type: 'result';
          subtype: 'error_max_turns' | 'error_during_execution';
          uuid: UUID;
          session_id: string;
          duration_ms: number;
          duration_api_ms: number;
          is_error: boolean;
          num_turns: number;
          total_cost_usd: number;
          usage: NonNullableUsage;
          permission_denials: SDKPermissionDenial[];
        }

### `SDKSystemMessage`

System initialization message.

    type SDKSystemMessage = {
      type: 'system';
      subtype: 'init';
      uuid: UUID;
      session_id: string;
      apiKeySource: ApiKeySource;
      cwd: string;
      tools: string[];
      mcp_servers: {
        name: string;
        status: string;
      }[];
      model: string;
      permissionMode: PermissionMode;
      slash_commands: string[];
      output_style: string;
    }

### `SDKPartialAssistantMessage`

Streaming partial message (only when `includePartialMessages` is true).

    type SDKPartialAssistantMessage = {
      type: 'stream_event';
      event: RawMessageStreamEvent; // From Anthropic SDK
      parent_tool_use_id: string | null;
      uuid: UUID;
      session_id: string;
    }

### `SDKCompactBoundaryMessage`

Message indicating a conversation compaction boundary.

    type SDKCompactBoundaryMessage = {
      type: 'system';
      subtype: 'compact_boundary';
      uuid: UUID;
      session_id: string;
      compact_metadata: {
        trigger: 'manual' | 'auto';
        pre_tokens: number;
      };
    }

### `SDKPermissionDenial`

Information about a denied tool use.

    type SDKPermissionDenial = {
      tool_name: string;
      tool_use_id: string;
      tool_input: ToolInput;
    }

## Hook Types

### `HookEvent`

Available hook events.

    type HookEvent = 
      | 'PreToolUse'
      | 'PostToolUse'
      | 'Notification'
      | 'UserPromptSubmit'
      | 'SessionStart'
      | 'SessionEnd'
      | 'Stop'
      | 'SubagentStop'
      | 'PreCompact';

### `HookCallback`

Hook callback function type.

    type HookCallback = (
      input: HookInput, // Union of all hook input types
      toolUseID: string | undefined,
      options: { signal: AbortSignal }
    ) => Promise<HookJSONOutput>;

### `HookCallbackMatcher`

Hook configuration with optional matcher.

    interface HookCallbackMatcher {
      matcher?: string;
      hooks: HookCallback[];
    }

### `HookInput`

Union type of all hook input types.

    type HookInput = 
      | PreToolUseHookInput
      | PostToolUseHookInput
      | NotificationHookInput
      | UserPromptSubmitHookInput
      | SessionStartHookInput
      | SessionEndHookInput
      | StopHookInput
      | SubagentStopHookInput
      | PreCompactHookInput;

### `BaseHookInput`

Base interface that all hook input types extend.

    type BaseHookInput = {
      session_id: string;
      transcript_path: string;
      cwd: string;
      permission_mode?: string;
    }

#### `PreToolUseHookInput`

    type PreToolUseHookInput = BaseHookInput & {
      hook_event_name: 'PreToolUse';
      tool_name: string;
      tool_input: ToolInput;
    }

#### `PostToolUseHookInput`

    type PostToolUseHookInput = BaseHookInput & {
      hook_event_name: 'PostToolUse';
      tool_name: string;
      tool_input: ToolInput;
      tool_response: ToolOutput;
    }

#### `NotificationHookInput`

    type NotificationHookInput = BaseHookInput & {
      hook_event_name: 'Notification';
      message: string;
      title?: string;
    }

#### `UserPromptSubmitHookInput`

    type UserPromptSubmitHookInput = BaseHookInput & {
      hook_event_name: 'UserPromptSubmit';
      prompt: string;
    }

#### `SessionStartHookInput`

    type SessionStartHookInput = BaseHookInput & {
      hook_event_name: 'SessionStart';
      source: 'startup' | 'resume' | 'clear' | 'compact';
    }

#### `SessionEndHookInput`

    type SessionEndHookInput = BaseHookInput & {
      hook_event_name: 'SessionEnd';
      reason: 'clear' | 'logout' | 'prompt_input_exit' | 'other';
    }

#### `StopHookInput`

    type StopHookInput = BaseHookInput & {
      hook_event_name: 'Stop';
      stop_hook_active: boolean;
    }

#### `SubagentStopHookInput`

    type SubagentStopHookInput = BaseHookInput & {
      hook_event_name: 'SubagentStop';
      stop_hook_active: boolean;
    }

#### `PreCompactHookInput`

    type PreCompactHookInput = BaseHookInput & {
      hook_event_name: 'PreCompact';
      trigger: 'manual' | 'auto';
      custom_instructions: string | null;
    }

### `HookJSONOutput`

Hook return value.

    type HookJSONOutput = AsyncHookJSONOutput | SyncHookJSONOutput;

#### `AsyncHookJSONOutput`

    type AsyncHookJSONOutput = {
      async: true;
      asyncTimeout?: number;
    }

#### `SyncHookJSONOutput`

    type SyncHookJSONOutput = {
      continue?: boolean;
      suppressOutput?: boolean;
      stopReason?: string;
      decision?: 'approve' | 'block';
      systemMessage?: string;
      reason?: string;
      hookSpecificOutput?:
        | {
            hookEventName: 'PreToolUse';
            permissionDecision?: 'allow' | 'deny' | 'ask';
            permissionDecisionReason?: string;
          }
        | {
            hookEventName: 'UserPromptSubmit';
            additionalContext?: string;
          }
        | {
            hookEventName: 'SessionStart';
            additionalContext?: string;
          }
        | {
            hookEventName: 'PostToolUse';
            additionalContext?: string;
          };
    }

## Tool Input Types

Documentation of input schemas for all built-in Claude Code tools. These types are exported from `@anthropic-ai/claude-agent-sdk` and can be used for type-safe tool interactions.

### `ToolInput`

**Note:** This is a documentation-only type for clarity. It represents the union of all tool input types.

    type ToolInput = 
      | AgentInput
      | BashInput
      | BashOutputInput
      | FileEditInput
      | FileReadInput
      | FileWriteInput
      | GlobInput
      | GrepInput
      | KillShellInput
      | NotebookEditInput
      | WebFetchInput
      | WebSearchInput
      | TodoWriteInput
      | ExitPlanModeInput
      | ListMcpResourcesInput
      | ReadMcpResourceInput;

### Task

**Tool name:** `Task`

    interface AgentInput {
      /**
       * A short (3-5 word) description of the task
       */
      description: string;
      /**
       * The task for the agent to perform
       */
      prompt: string;
      /**
       * The type of specialized agent to use for this task
       */
      subagent_type: string;
    }

Launches a new agent to handle complex, multi-step tasks autonomously.

### Bash

**Tool name:** `Bash`

    interface BashInput {
      /**
       * The command to execute
       */
      command: string;
      /**
       * Optional timeout in milliseconds (max 600000)
       */
      timeout?: number;
      /**
       * Clear, concise description of what this command does in 5-10 words
       */
      description?: string;
      /**
       * Set to true to run this command in the background
       */
      run_in_background?: boolean;
    }

Executes bash commands in a persistent shell session with optional timeout and background execution.

### BashOutput

**Tool name:** `BashOutput`

    interface BashOutputInput {
      /**
       * The ID of the background shell to retrieve output from
       */
      bash_id: string;
      /**
       * Optional regex to filter output lines
       */
      filter?: string;
    }

Retrieves output from a running or completed background bash shell.

### Edit

**Tool name:** `Edit`

    interface FileEditInput {
      /**
       * The absolute path to the file to modify
       */
      file_path: string;
      /**
       * The text to replace
       */
      old_string: string;
      /**
       * The text to replace it with (must be different from old_string)
       */
      new_string: string;
      /**
       * Replace all occurrences of old_string (default false)
       */
      replace_all?: boolean;
    }

Performs exact string replacements in files.

### Read

**Tool name:** `Read`

    interface FileReadInput {
      /**
       * The absolute path to the file to read
       */
      file_path: string;
      /**
       * The line number to start reading from
       */
      offset?: number;
      /**
       * The number of lines to read
       */
      limit?: number;
    }

Reads files from the local filesystem, including text, images, PDFs, and Jupyter notebooks.

### Write

**Tool name:** `Write`

    interface FileWriteInput {
      /**
       * The absolute path to the file to write
       */
      file_path: string;
      /**
       * The content to write to the file
       */
      content: string;
    }

Writes a file to the local filesystem, overwriting if it exists.

### Glob

**Tool name:** `Glob`

    interface GlobInput {
      /**
       * The glob pattern to match files against
       */
      pattern: string;
      /**
       * The directory to search in (defaults to cwd)
       */
      path?: string;
    }

Fast file pattern matching that works with any codebase size.

### Grep

**Tool name:** `Grep`

    interface GrepInput {
      /**
       * The regular expression pattern to search for
       */
      pattern: string;
      /**
       * File or directory to search in (defaults to cwd)
       */
      path?: string;
      /**
       * Glob pattern to filter files (e.g. "*.js")
       */
      glob?: string;
      /**
       * File type to search (e.g. "js", "py", "rust")
       */
      type?: string;
      /**
       * Output mode: "content", "files_with_matches", or "count"
       */
      output_mode?: 'content' | 'files_with_matches' | 'count';
      /**
       * Case insensitive search
       */
      '-i'?: boolean;
      /**
       * Show line numbers (for content mode)
       */
      '-n'?: boolean;
      /**
       * Lines to show before each match
       */
      '-B'?: number;
      /**
       * Lines to show after each match
       */
      '-A'?: number;
      /**
       * Lines to show before and after each match
       */
      '-C'?: number;
      /**
       * Limit output to first N lines/entries
       */
      head_limit?: number;
      /**
       * Enable multiline mode
       */
      multiline?: boolean;
    }

Powerful search tool built on ripgrep with regex support.

### KillBash

**Tool name:** `KillBash`

    interface KillShellInput {
      /**
       * The ID of the background shell to kill
       */
      shell_id: string;
    }

Kills a running background bash shell by its ID.

### NotebookEdit

**Tool name:** `NotebookEdit`

    interface NotebookEditInput {
      /**
       * The absolute path to the Jupyter notebook file
       */
      notebook_path: string;
      /**
       * The ID of the cell to edit
       */
      cell_id?: string;
      /**
       * The new source for the cell
       */
      new_source: string;
      /**
       * The type of the cell (code or markdown)
       */
      cell_type?: 'code' | 'markdown';
      /**
       * The type of edit (replace, insert, delete)
       */
      edit_mode?: 'replace' | 'insert' | 'delete';
    }

Edits cells in Jupyter notebook files.

### WebFetch

**Tool name:** `WebFetch`

    interface WebFetchInput {
      /**
       * The URL to fetch content from
       */
      url: string;
      /**
       * The prompt to run on the fetched content
       */
      prompt: string;
    }

Fetches content from a URL and processes it with an AI model.

### WebSearch

**Tool name:** `WebSearch`

    interface WebSearchInput {
      /**
       * The search query to use
       */
      query: string;
      /**
       * Only include results from these domains
       */
      allowed_domains?: string[];
      /**
       * Never include results from these domains
       */
      blocked_domains?: string[];
    }

Searches the web and returns formatted results.

### TodoWrite

**Tool name:** `TodoWrite`

    interface TodoWriteInput {
      /**
       * The updated todo list
       */
      todos: Array<{
        /**
         * The task description
         */
        content: string;
        /**
         * The task status
         */
        status: 'pending' | 'in_progress' | 'completed';
        /**
         * Active form of the task description
         */
        activeForm: string;
      }>;
    }

Creates and manages a structured task list for tracking progress.

### ExitPlanMode

**Tool name:** `ExitPlanMode`

    interface ExitPlanModeInput {
      /**
       * The plan to run by the user for approval
       */
      plan: string;
    }

Exits planning mode and prompts the user to approve the plan.

### ListMcpResources

**Tool name:** `ListMcpResources`

    interface ListMcpResourcesInput {
      /**
       * Optional server name to filter resources by
       */
      server?: string;
    }

Lists available MCP resources from connected servers.

### ReadMcpResource

**Tool name:** `ReadMcpResource`

    interface ReadMcpResourceInput {
      /**
       * The MCP server name
       */
      server: string;
      /**
       * The resource URI to read
       */
      uri: string;
    }

Reads a specific MCP resource from a server.

## Tool Output Types

Documentation of output schemas for all built-in Claude Code tools. These types represent the actual response data returned by each tool.

### `ToolOutput`

**Note:** This is a documentation-only type for clarity. It represents the union of all tool output types.

    type ToolOutput = 
      | TaskOutput
      | BashOutput
      | BashOutputToolOutput
      | EditOutput
      | ReadOutput
      | WriteOutput
      | GlobOutput
      | GrepOutput
      | KillBashOutput
      | NotebookEditOutput
      | WebFetchOutput
      | WebSearchOutput
      | TodoWriteOutput
      | ExitPlanModeOutput
      | ListMcpResourcesOutput
      | ReadMcpResourceOutput;

### Task

**Tool name:** `Task`

    interface TaskOutput {
      /**
       * Final result message from the subagent
       */
      result: string;
      /**
       * Token usage statistics
       */
      usage?: {
        input_tokens: number;
        output_tokens: number;
        cache_creation_input_tokens?: number;
        cache_read_input_tokens?: number;
      };
      /**
       * Total cost in USD
       */
      total_cost_usd?: number;
      /**
       * Execution duration in milliseconds
       */
      duration_ms?: number;
    }

Returns the final result from the subagent after completing the delegated task.

### Bash

**Tool name:** `Bash`

    interface BashOutput {
      /**
       * Combined stdout and stderr output
       */
      output: string;
      /**
       * Exit code of the command
       */
      exitCode: number;
      /**
       * Whether the command was killed due to timeout
       */
      killed?: boolean;
      /**
       * Shell ID for background processes
       */
      shellId?: string;
    }

Returns command output with exit status. Background commands return immediately with a shellId.

### BashOutput

**Tool name:** `BashOutput`

    interface BashOutputToolOutput {
      /**
       * New output since last check
       */
      output: string;
      /**
       * Current shell status
       */
      status: 'running' | 'completed' | 'failed';
      /**
       * Exit code (when completed)
       */
      exitCode?: number;
    }

Returns incremental output from background shells.

### Edit

**Tool name:** `Edit`

    interface EditOutput {
      /**
       * Confirmation message
       */
      message: string;
      /**
       * Number of replacements made
       */
      replacements: number;
      /**
       * File path that was edited
       */
      file_path: string;
    }

Returns confirmation of successful edits with replacement count.

### Read

**Tool name:** `Read`

    type ReadOutput = 
      | TextFileOutput
      | ImageFileOutput
      | PDFFileOutput
      | NotebookFileOutput;

    interface TextFileOutput {
      /**
       * File contents with line numbers
       */
      content: string;
      /**
       * Total number of lines in file
       */
      total_lines: number;
      /**
       * Lines actually returned
       */
      lines_returned: number;
    }

    interface ImageFileOutput {
      /**
       * Base64 encoded image data
       */
      image: string;
      /**
       * Image MIME type
       */
      mime_type: string;
      /**
       * File size in bytes
       */
      file_size: number;
    }

    interface PDFFileOutput {
      /**
       * Array of page contents
       */
      pages: Array<{
        page_number: number;
        text?: string;
        images?: Array<{
          image: string;
          mime_type: string;
        }>;
      }>;
      /**
       * Total number of pages
       */
      total_pages: number;
    }

    interface NotebookFileOutput {
      /**
       * Jupyter notebook cells
       */
      cells: Array<{
        cell_type: 'code' | 'markdown';
        source: string;
        outputs?: any[];
        execution_count?: number;
      }>;
      /**
       * Notebook metadata
       */
      metadata?: Record<string, any>;
    }

Returns file contents in format appropriate to file type.

### Write

**Tool name:** `Write`

    interface WriteOutput {
      /**
       * Success message
       */
      message: string;
      /**
       * Number of bytes written
       */
      bytes_written: number;
      /**
       * File path that was written
       */
      file_path: string;
    }

Returns confirmation after successfully writing the file.

### Glob

**Tool name:** `Glob`

    interface GlobOutput {
      /**
       * Array of matching file paths
       */
      matches: string[];
      /**
       * Number of matches found
       */
      count: number;
      /**
       * Search directory used
       */
      search_path: string;
    }

Returns file paths matching the glob pattern, sorted by modification time.

### Grep

**Tool name:** `Grep`

    type GrepOutput = 
      | GrepContentOutput
      | GrepFilesOutput
      | GrepCountOutput;

    interface GrepContentOutput {
      /**
       * Matching lines with context
       */
      matches: Array<{
        file: string;
        line_number?: number;
        line: string;
        before_context?: string[];
        after_context?: string[];
      }>;
      /**
       * Total number of matches
       */
      total_matches: number;
    }

    interface GrepFilesOutput {
      /**
       * Files containing matches
       */
      files: string[];
      /**
       * Number of files with matches
       */
      count: number;
    }

    interface GrepCountOutput {
      /**
       * Match counts per file
       */
      counts: Array<{
        file: string;
        count: number;
      }>;
      /**
       * Total matches across all files
       */
      total: number;
    }

Returns search results in the format specified by output_mode.

### KillBash

**Tool name:** `KillBash`

    interface KillBashOutput {
      /**
       * Success message
       */
      message: string;
      /**
       * ID of the killed shell
       */
      shell_id: string;
    }

Returns confirmation after terminating the background shell.

### NotebookEdit

**Tool name:** `NotebookEdit`

    interface NotebookEditOutput {
      /**
       * Success message
       */
      message: string;
      /**
       * Type of edit performed
       */
      edit_type: 'replaced' | 'inserted' | 'deleted';
      /**
       * Cell ID that was affected
       */
      cell_id?: string;
      /**
       * Total cells in notebook after edit
       */
      total_cells: number;
    }

Returns confirmation after modifying the Jupyter notebook.

### WebFetch

**Tool name:** `WebFetch`

    interface WebFetchOutput {
      /**
       * AI model's response to the prompt
       */
      response: string;
      /**
       * URL that was fetched
       */
      url: string;
      /**
       * Final URL after redirects
       */
      final_url?: string;
      /**
       * HTTP status code
       */
      status_code?: number;
    }

Returns the AI's analysis of the fetched web content.

### WebSearch

**Tool name:** `WebSearch`

    interface WebSearchOutput {
      /**
       * Search results
       */
      results: Array<{
        title: string;
        url: string;
        snippet: string;
        /**
         * Additional metadata if available
         */
        metadata?: Record<string, any>;
      }>;
      /**
       * Total number of results
       */
      total_results: number;
      /**
       * The query that was searched
       */
      query: string;
    }

Returns formatted search results from the web.

### TodoWrite

**Tool name:** `TodoWrite`

    interface TodoWriteOutput {
      /**
       * Success message
       */
      message: string;
      /**
       * Current todo statistics
       */
      stats: {
        total: number;
        pending: number;
        in_progress: number;
        completed: number;
      };
    }

Returns confirmation with current task statistics.

### ExitPlanMode

**Tool name:** `ExitPlanMode`

    interface ExitPlanModeOutput {
      /**
       * Confirmation message
       */
      message: string;
      /**
       * Whether user approved the plan
       */
      approved?: boolean;
    }

Returns confirmation after exiting plan mode.

### ListMcpResources

**Tool name:** `ListMcpResources`

    interface ListMcpResourcesOutput {
      /**
       * Available resources
       */
      resources: Array<{
        uri: string;
        name: string;
        description?: string;
        mimeType?: string;
        server: string;
      }>;
      /**
       * Total number of resources
       */
      total: number;
    }

Returns list of available MCP resources.

### ReadMcpResource

**Tool name:** `ReadMcpResource`

    interface ReadMcpResourceOutput {
      /**
       * Resource contents
       */
      contents: Array<{
        uri: string;
        mimeType?: string;
        text?: string;
        blob?: string;
      }>;
      /**
       * Server that provided the resource
       */
      server: string;
    }

Returns the contents of the requested MCP resource.

## Permission Types

### `PermissionUpdate`

Operations for updating permissions.

    type PermissionUpdate = 
      | {
          type: 'addRules';
          rules: PermissionRuleValue[];
          behavior: PermissionBehavior;
          destination: PermissionUpdateDestination;
        }
      | {
          type: 'replaceRules';
          rules: PermissionRuleValue[];
          behavior: PermissionBehavior;
          destination: PermissionUpdateDestination;
        }
      | {
          type: 'removeRules';
          rules: PermissionRuleValue[];
          behavior: PermissionBehavior;
          destination: PermissionUpdateDestination;
        }
      | {
          type: 'setMode';
          mode: PermissionMode;
          destination: PermissionUpdateDestination;
        }
      | {
          type: 'addDirectories';
          directories: string[];
          destination: PermissionUpdateDestination;
        }
      | {
          type: 'removeDirectories';
          directories: string[];
          destination: PermissionUpdateDestination;
        }

### `PermissionBehavior`

    type PermissionBehavior = 'allow' | 'deny' | 'ask';

### `PermissionUpdateDestination`

    type PermissionUpdateDestination = 
      | 'userSettings'     // Global user settings
      | 'projectSettings'  // Per-directory project settings
      | 'localSettings'    // Gitignored local settings
      | 'session'          // Current session only

### `PermissionRuleValue`

    type PermissionRuleValue = {
      toolName: string;
      ruleContent?: string;
    }

## Other Types

### `ApiKeySource`

    type ApiKeySource = 'user' | 'project' | 'org' | 'temporary';

### `ConfigScope`

    type ConfigScope = 'local' | 'user' | 'project';

### `NonNullableUsage`

A version of [`Usage`](https://platform.claude.com/docs/en/agent-sdk/typescript#usage) with all nullable fields made non-nullable.

    type NonNullableUsage = {
      [K in keyof Usage]: NonNullable<Usage[K]>;
    }

### `Usage`

Token usage statistics (from `@anthropic-ai/sdk`).

    type Usage = {
      input_tokens: number | null;
      output_tokens: number | null;
      cache_creation_input_tokens?: number | null;
      cache_read_input_tokens?: number | null;
    }

### `CallToolResult`

MCP tool result type (from `@modelcontextprotocol/sdk/types.js`).

    type CallToolResult = {
      content: Array<{
        type: 'text' | 'image' | 'resource';
        // Additional fields vary by type
      }>;
      isError?: boolean;
    }

### `AbortError`

Custom error class for abort operations.

    class AbortError extends Error {}

## See also

- [SDK overview](https://platform.claude.com/docs/en/agent-sdk/overview) - General SDK concepts
- [Python SDK reference](https://platform.claude.com/docs/en/agent-sdk/python) - Python SDK documentation
- [CLI reference](https://code.claude.com/docs/en/cli-reference) - Command-line interface
- [Common workflows](https://code.claude.com/docs/en/common-workflows) - Step-by-step guides