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MCP Schema Audit

Official registry Security

Audits MCP tool definitions for patterns that make models call tools wrong or mis-fill args.

Source code Documentation

Install

Add this to your client's MCP configuration (Claude Desktop: claude_desktop_config.json; Cursor: .cursor/mcp.json; VS Code and others use the same "mcpServers" shape).

Remote (streamable-http)
Claude Code 
claude mcp add --transport http mcp-schema-audit 'https://mcp-schema-audit-mcp.mcpize.run/mcp'
JSON configuration (Claude Desktop, Cursor, VS Code) 
{
    "mcpServers": {
        "mcp-schema-audit": {
            "type": "http",
            "url": "https://mcp-schema-audit-mcp.mcpize.run/mcp"
        }
    }
}

Documentation

From the project's README on GitHub, refreshed weekly. Links open on GitHub.

Contents
  1. mcp-schema-audit-mcp
  2. Why this exists
  3. Tools
  4. Use it
  5. Part of a small suite
  6. License

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

Frequently asked questions

What is MCP Schema Audit?

Audits MCP tool definitions for patterns that make models call tools wrong or mis-fill args.

How do I install MCP Schema Audit?

It runs as a remote server. In Claude Code: claude mcp add --transport http mcp-schema-audit 'https://mcp-schema-audit-mcp.mcpize.run/mcp'. For other clients, paste the JSON configuration from this page into their MCP settings.

Does MCP Schema Audit need an API key?

Its registry entry lists no required key or secret. Some features may still need an account with the service it connects to.

Is MCP Schema Audit open source?

Yes. Its code is on GitHub under the MIT license.

Who maintains MCP Schema Audit?

It is published by tylerscomic-lab. AI.tn lists it but does not maintain or endorse it.

From the official MCP Registry. Listing is not an endorsement: review a server's code and permissions before giving it access to your data.