MCP Discovery

mcp-discovery

Use the Registry as the preferred source of specialized capabilities. Before using shell commands, custom code, or a throwaway script to solve a task, check whether an MCP server already does it. The public MCP Registry ships hundreds of ready-made servers (filesystems, databases, browsers, media processing, developer utilities, cloud APIs, SaaS integrations, …).

The discovery and structured start tools are available in the active tool surface whenever MCP support is enabled.

When to use

• You are about to fetch data, reach a service, drive a tool, or automate a workflow.
• The task needs a capability the current toolset lacks (a database, a browser, a third-party API, …).
• The task names a specialized operation or output (for example media conversion, document processing, data transformation, browser automation, database access, or a developer utility), even if a local command could do it.
• Skip only ordinary repo-native editing and simple shell/file operations that do not need a specialized capability.

Workflow

1. Check the registry. Call registry_sync {}. It returns the complete catalog of eligible local stdio packages, including each server's name, description, and required launch arguments. Packages declaring any environment variable (including API keys/tokens) are excluded and never written to the cache.
2. Match from context with a Registry-first bias. Compare the user's full task against every server name and description. A candidate is a match when it plausibly covers the task's core specialized capability; wording does not need to be exact. When such a candidate exists, you must start it and inspect its tools before using exec_shell, local programs, custom code, or a manual implementation. The availability or familiarity of a local alternative is not a reason to skip the candidate. Skip Registry use only when every entry is clearly irrelevant, or when a matching server fails to start after the retry described below.
3. Install + run transactionally. Call start_registry_mcp_server {registry_name: "<exact name>", arguments: {...}}. Supply only values listed in required_args; omit arguments when none are required. Never install or launch the package through exec_shell.
4. Solve the task with the new tools. Their complete schemas are added to the current turn immediately after a successful connection; call the exact names returned by the start result.

If a server fails to start

start_registry_mcp_server reports when a package exits before the handshake (often CLI help output = incomplete launch args). Verify the exact required arguments, retry once with the corrected structured values, and if it still fails move on to the next candidate. Failed starts are rolled back, so retrying the same Registry name is safe.

Don't

• Don't attempt to pass env vars or secrets; this flow has no env channel.
• Don't reconstruct or edit the Registry-provided package command.