Kiro Custom Agents

Kiro Custom Agents

Overview

Guide for creating and configuring Kiro CLI custom agents — JSON configuration files that customize Kiro's behavior for specific workflows.

Quick Start

Create an agent interactively in a Kiro CLI session:

/agent generate

Or via CLI:

kiro-cli agent create --name my-agent

Or manually create a JSON file:

• Global: ~/.kiro/agents/<name>.json
• Local (project): .kiro/agents/<name>.json

Minimal agent:

{
  "name": "my-agent",
  "description": "A custom agent for my workflow",
  "tools": ["read", "write"],
  "allowedTools": ["read"],
  "resources": ["file://README.md"],
  "prompt": "You are a helpful coding assistant"
}

Workflow

1. Clarify the agent's purpose and target workflow
2. Determine which tools are needed (tools) and which to pre-approve (allowedTools)
3. Identify MCP servers if external tools are needed
4. Choose resources to load (files, skills, knowledge bases)
5. Add hooks for dynamic context or validation
6. Configure tool restrictions via toolsSettings
7. Write the JSON config file
8. Test: /agent list → /agent swap <name> → /tools → test workflows

Key Concepts

tools: What the agent CAN use. "*" = all, "@builtin" = built-in only, "@server" = all from MCP server.

allowedTools: What runs WITHOUT permission prompts. Supports glob patterns (@server/read_*, @builtin). Does NOT support "*".

toolAliases: Remap tool names to resolve naming collisions or create intuitive names.

resources: Context loaded at startup. file:// = immediate, skill:// = on-demand, knowledgeBase = indexed search.

hooks: Commands at lifecycle points. agentSpawn, userPromptSubmit, preToolUse (can block), postToolUse, stop.

steering: NOT auto-included in custom agents. Add explicitly: "resources": ["file://.kiro/steering/**/*.md"]

Updating This Skill

Reference files have Source: <URL> headers linking to official Kiro docs. To check for updates:

python3 scripts/fetch_docs.py --diff   # Check which sources changed
python3 scripts/fetch_docs.py          # Fetch and save raw HTML to references/raw/

After fetching, compare references/raw/*.html against existing references/*.md files and update the summaries as needed. Each reference file is a curated summary — not a raw copy — so review changes before updating.

References

• Full config schema: See references/configuration-reference.md for all fields, patterns, and best practices
• Working examples: See references/examples.md for AWS, dev workflow, code review, project-specific, and remote MCP agents
• Hooks: See references/hooks.md for hook types, matchers, exit codes, MCP examples, and use cases
• MCP setup: See references/mcp.md for MCP server configuration (CLI, mcp.json, agent config, remote)
• Steering: See references/steering.md for steering file scope, team steering, custom files, and integration with agents
• Code intelligence: See references/code-intelligence.md for LSP setup, pattern search/rewrite, /code commands, and language server usage
• Context management: See references/context.md for agent resources, session context, knowledge bases, and compaction
• Subagents: See references/subagents.md for subagent tool availability, availableAgents/trustedAgents config, and usage
• Prompts: See references/prompts.md for /prompts commands, MCP prompt arguments, and storage priority
• Images: See references/images.md for image input methods, supported formats, and use cases
• Troubleshooting: See references/troubleshooting.md for common issues and testing checklist

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