What problem does it solve? Building a Model Context Protocol server from scratch requires understanding JSON-RPC 2.0 framing over stdio, tool schema design, and APX registration mechanics. This Skill provides the minimum viable server patterns, tool design rules, and debugging commands needed to expose a new tool surface to APX agents without protocol trial-and-error. ## Core Features & Use Cases - Stack Selection Guidance: Choose between Python FastMCP, the Node @modelcontextprotocol/sdk, or raw JSON-RPC based on your library ecosystem. - Minimum Viable Server Templates: Copy-ready Python and TypeScript implementations covering initialize, tools/list, and tools/call handlers. - Tool Design Rules: Enforce snake_case naming, JSON Schema draft-07 input schemas, structured return values, and proper error propagation via isError. - Secrets Management: Register servers with apx mcp add using runtime scope so tokens land in chmod 0600 files that are never committed. - Use Case: You want your APX agent to query an internal inventory API. Write a FastMCP server with search_inventory and get_stock tools, register it with apx mcp add, then verify with apx mcp tools and apx mcp run. ## Quick Start Ask the agent to scaffold a new FastMCP server with two tools and register it in APX using apx mcp add with runtime scope.
