Thanks for helping improve the MCP conformance suite!
The most valuable contributions are new conformance scenarios that cover under-tested parts of the MCP spec. If you're not sure where to start, ask in #conformance-testing-wg on the MCP Contributors Discord.
Open an issue first — whether you've found a bug or want to propose a new scenario. A short discussion up front saves everyone time on PRs that overlap existing work or head in a direction we're not going.
Then read AGENTS.md — it's the design guide for scenarios and checks. The short version:
- Fewer scenarios, more checks. Each scenario spins up its own server and runs in CI for every SDK. One scenario with 10 checks beats 10 scenarios with one check each.
- Prove it passes and fails. Extend the existing everything-client/server to pass your scenario, and show (or include) a failing case.
- Reuse the CLI runner. Don't add parallel entry points.
If you're using an AI agent to help, please don't point it at the repo with a generic "find bugs" prompt — give it a specific MUST from the spec or an open issue to work on. See AGENTS.md for details.
npm install
npm run build
npm testThis repo uses npm — don't commit pnpm-lock.yaml or yarn.lock.
# Against the bundled TypeScript example
npm run build
node dist/index.js client --command "tsx examples/clients/typescript/everything-client.ts" --scenario <your-scenario>
# Against a server
node dist/index.js server --url http://localhost:3000/mcp --scenario <your-scenario>See the README for full CLI options and the SDK Integration Guide for testing against a real SDK.
- Register your scenario in the right suite in
src/scenarios/index.ts - Run against at least one real SDK before opening the PR — we'll ask what the output looked like
- Keep PRs focused; one feature or scenario group at a time