mcp-covenant

Contract & breaking-change detection for Model Context Protocol servers — semver for your MCP interface.

When you ship a typed library you have a public API and tooling that screams when you break
it. MCP servers have neither: they just serve whatever tools/list returns today. Rename a
tool, add a required argument, narrow an enum — every agent built on your server breaks, and
nothing in your pipeline noticed.

mcp-covenant is one static binary that snapshots your server's interface into a committed
lockfile and fails CI when a change would break existing clients — classified the way a
human would: breaking / minor / patch.

```text
$ mcp-covenant check --baseline mcp-covenant.lock -- node dist/server.js
mcp-covenant: 3 change(s) — required version bump: MAJOR

BREAKING (2)
x tool:legacy — tool was removed [tool.removed]
x tool:search → inputSchema.properties.limit — new required property [schema.property.required.added]
MINOR (1)
+ tool:newtool — new tool [tool.added]