MCP Compliance MCP server

@yawlabs/mcp-compliance

Test any MCP server for spec compliance. Two test suites — 88 tests for MCP 2025-11-25 and 103 tests for MCP 2026-07-28 — covering transport, lifecycle, tools, resources, prompts, error handling, schema validation, and security. The tool probes the server and grades the newest spec revision it speaks, or you pin one with --spec-version. Works against HTTP endpoints (https://my-server.com/mcp) and stdio servers (npx @modelcontextprotocol/server-filesystem /tmp) alike. CLI, MCP server, and programmatic API.

Built and maintained by Yaw Labs.

One click adds this to your local Yaw MCP config so it's available in every Yaw Terminal session. Or install manually below.

Why this tool?

MCP servers are multiplying fast — but most ship without compliance testing. Broken transport handling, missing error codes, malformed schemas, and silent capability violations are common. Hand-rolling test scripts is tedious and incomplete.

This tool solves that:

• Two spec revisions, one tool — 88 tests for MCP 2025-11-25 (the initialize + session era) and 103 tests for MCP 2026-07-28 (stateless, per-request _meta, server/discover, caching hints, MRTR). Both cover the same 8 categories: transport, lifecycle, tools, resources, prompts, error handling, schema validation, and security. HTTP-specific tests (CORS, TLS, header validation, rate limiting) are gated out on stdio: the 2025-11-25 suite runs 85 tests on HTTP and 55 on stdio, the 2026-07-28 suite 99 and 75.
• Auto-detected revision — one server/discover probe tells the tool which era the server speaks; dual-era servers are graded against 2026-07-28 with a warning. Pin either revision with --spec-version. See Spec version.
• Capability-driven — tests adapt to what the server declares. If it says it supports tools, tool tests become required. No false failures for features the server doesn't claim.
• Graded scoring — A-F letter grade with a weighted score (required tests 70%, optional 30%). One number to communicate compliance.
• CI-ready — --strict mode exits with code 1 on required test failures. Drop it into any pipeline.
• Spec-referenced — every test links to the exact section of the MCP specification it validates. No ambiguity about what's being tested or why.
• Three interfaces — CLI for humans, MCP server for AI assistants, programmatic API for integration.
• Published methodology — the testing methodology and rule catalog are open (CC BY 4.0) so anyone can build compatible tooling or fork the rules.

Quick start

Remote HTTP server:

npx @yawlabs/mcp-compliance@latest test https://my-server.com/mcp

Local stdio server (the vast majority of MCP servers on npm):

# Pass the command directly, Inspector-style
npx @yawlabs/mcp-compliance@latest test npx @modelcontextprotocol/server-filesystem /tmp

# Or a local build
npx @yawlabs/mcp-compliance@latest test node ./dist/server.js

Shortened. The full README is on GitHub.