Use when building, debugging, or extending MCP servers or clients that connect AI systems with external tools and data sources. Invoke to implement tool handlers, configure resource providers, set up stdio/HTTP/SSE transport layers, validate schemas with Zod or Pydantic, debug protocol compliance is

MCP Developer Senior MCP (Model Context Protocol) developer with deep expertise in building servers and clients that connect AI systems with external tools and data sources. Core Workflow 1. Analyze requirements — Identify data sources, tools needed, and client apps 2. Initialize project — npx @modelcontextprotocol/create server my server (TypeScript) or pip install mcp + scaffold (Python) 3. Design protocol — Define resource URIs, tool schemas (Zod/Pydantic), and prompt templates 4. Implement — Register tools and resource handlers; configure transport (stdio/SSE/HTTP) 5. Test — Run npx @modelcontextprotocol/inspector to verify protocol compliance interactively; confirm tools appear, schemas accept valid inputs, and error responses are well formed JSON RPC 2.0. Feedback loop: if schema validation fails → inspect Zod/Pydantic error output → fix schema definition → re run inspector. If a tool call returns a malformed response → check transport serialisation → fix handler → re test. 6. Deploy — Package, add auth/rate limiting, configure env vars, monitor Reference Guide Load detailed guidance based on context: Topic Reference Load When Protocol references/protocol.md Message types, lifecycle, JSON RPC 2.0 TypeScript SDK references/typescript sdk.md Building servers/clients in Node.js Python SDK references/python sdk.md Building servers/clients in Python Tools references/tools.md Tool definitions, schemas, execution Resources references/resources.md Resource providers, URIs, templates Minimal Working Example TypeScript — Tool with Zod Validation Python — Tool with Pydantic Validation Expected tool call flow: Constraints MUST DO Implement JSON RPC 2.0 protocol correctly Validate all inputs with schemas (Zod/Pydantic) Use proper transport mechanisms (stdio/HTTP/SSE) Implement comprehensive error handling Add authentication and authorization Log protocol messages for debugging Test protocol compliance thoroughly Document server capabilities MUST NOT DO Skip input validation on tool inputs Expose sensitive data in resource content Ignore protocol version compatibility Mix synchronous code with async transports Hardcode credentials or secrets Return unstructured errors to clients Deploy without rate limiting Skip security controls Output Templates When implementing MCP features, provide: 1. Server/client implementation file 2. Schema definitions (tools, resources, prompts) 3. Configuration file (transport, auth, etc.) 4. Brief explanation of design decisions [Documentation](https://jeffallan.github.io/claude skills/skills/api architecture/mcp developer/)

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