Kick the tires on MCP servers
before you install them.
tirekick connects to a server, pulls its tool list, and flags the schemas that break strict clients like Claude Code.
Paste any remote server's streamable-HTTP endpoint. Nothing is stored.
What gets checked
Schema conformance
Every inputSchema and outputSchema is compiled against the JSON Schema draft 2020-12 meta-schema, the same bar the Claude API applies, and input schema roots must be type object.
graded as Interop
Strict-regex safety
Every pattern is linted for constructs that are valid ECMA-262 but rejected by RE2/Rust-style engines: lookaround, backreferences, and unescaped [ inside a character class.
graded as Safety
Description quality
Agents pick tools by description. Missing or very short descriptions, and tools with no input schema at all, are flagged: the server runs, but agents will use it badly.
graded as Agent ergonomics
Why this exists
Our own MCP server shipped a schema bug that bricked Claude Code sessions. tirekick is the check we wished we'd run first: read the incident.
Open source
The validator runs on your machine too: npx tirekick check <url>. Get it on npm or read the code on GitHub.
The directory
The same checks run in bulk against the public MCP registry. Browse graded servers or read how grading works.
Kick the tires from your own CI
- Check a URL, npm package, or saved
tools/list - Exits non-zero on errors, ready for CI
- MIT-licensed, grade reproducible
npx tirekick check https://your-server/mcp