Schema Audit MCP Server

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'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 — free tier included, $7/mo for higher limits.

Self-host:

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 (DST-correct cron validation), regex-safety-audit-mcp (ReDoS detection), and claude-cost-audit-mcp (exact Claude API cost + cache-economics calculator).

License

MIT