MCP Schema Checker
An MCP schema checker validates what a server declares before you connect: it completes the initialize handshake, requests tools/list, and checks tool names, descriptions, and input/output JSON schemas without ever invoking a tool. The need is measurable. In our weekly scan of all 9,991 remote endpoints in the official MCP Registry (October 2026), responding servers produced 46,216 property-level schema findings, mostly missing descriptions, which is the text an LLM reads to decide when to call a tool. Numbers and method: State of MCP Servers, October 2026.
Read the full guide in the source repository.
npx @eidonze/mcpreflight@0.1.5 schema https://your-mcp.example/mcp --json
Checks initialize, tools/list, names, descriptions, object schemas, declared properties, required fields, and property descriptions. It does not invoke tools or prove runtime behavior.