How MCP Clients Discover Tools

Discovery turns a server into a dynamic capability provider rather than a hardcoded list of functions.

List, paginate, cache

A client lists tools, follows pagination where needed, and can cache the resulting catalog according to server guidance or runtime configuration.

Discovery is not automatic permission

A discovered tool may still be inappropriate for a given agent or user. Apply allowlists, role checks, and task-specific filtering before model exposure.

Descriptions matter

The model usually sees tool names, descriptions, and schemas. Poor descriptions can cause wrong tool selection even when the protocol layer is flawless.