# mcp-schema-audit-mcp

[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](LICENSE)
[![Live on MCPize](https://img.shields.io/badge/Live%20on-MCPize-6d28d9)](https://mcpize.com/mcp/mcp-schema-audit-mcp)

An MCP server that audits **other** MCP tool definitions and marketplace listings for the specific patterns that
make models call tools wrong, never call them, or mis-fill their parameters — vague descriptions, missing
parameter docs, non-verb-first naming, oversized enums, deeply nested schemas — plus [MCPize](https://mcpize.com)'s
own 500-character description limit, which fails at deploy time with no warning until you hit it.

Most tool-definition bugs don't throw errors. They just make a model call the wrong tool, or call the right tool
with the wrong arguments, silently and intermittently. This scores every tool 0-100 and tells you exactly which
line to fix.

## Why this exists

Verb-first naming, parameter descriptions, and schema depth aren't cosmetic — they measurably change how reliably
a model picks and fills a tool. This project encodes those patterns as an actual auditor instead of a blog post
you have to remember to re-read every time you write a new tool.

## Tools

### `audit_tool_definition`
Audit a single tool (name, description, inputSchema). Returns a 0-100 friendliness score and a list of concrete
issues, each with severity, why it matters, and the fix.

### `audit_tool_batch`
Same checks across an entire server's tool list, plus cross-tool checks: duplicate names, inconsistent naming
convention (snake_case vs camelCase mixed in one server), and a worst-offenders summary.

### `check_marketplace_description`
Validates a marketplace-facing short/long description against known platform limits — specifically catches
MCPize's 500-character short-description cap before you burn a deploy attempt finding out the hard way.

## Use it

**Hosted (recommended, no setup):** subscribe on [MCPize](https://mcpize.com/mcp/mcp-schema-audit-mcp) — free tier
included, $7/mo for higher limits.

**Self-host:**
```bash
npm install
node server.js
```
Exposes a Streamable HTTP MCP endpoint on `:8080` (`/mcp`), health check at `/health`.

## Part of a small suite

Built alongside three sibling correctness-audit tools for Claude Code / MCP builders:
[cron-schedule-audit-mcp](https://github.com/tylerscomic-lab/cron-schedule-audit-mcp) (DST-correct cron
validation), [regex-safety-audit-mcp](https://github.com/tylerscomic-lab/regex-safety-audit-mcp) (ReDoS
detection), and [claude-cost-audit-mcp](https://github.com/tylerscomic-lab/claude-cost-audit-mcp) (exact Claude
API cost + cache-economics calculator).

## License

MIT