MCPScore

A command-line tool for auditing MCP (Model Context Protocol) servers. MCPScore connects to your server, runs a comprehensive set of validation rules against it, and produces a severity-based report showing what's compliant and what needs attention.

Why MCPScore?

MCP servers that violate the spec fail silently in the worst place: inside someone else's AI agent. A missing tool description, an outdated protocol version, or an unencrypted endpoint won't crash your server — it will just make agents pick the wrong tool, drop your server from their registry, or leak traffic. MCPScore catches these issues in seconds, before your users do.

pip install mcpscore
mcpscore https://your-server.example/mcp

Documentation: docs.mcpscore.dev — including the full
scoring methodology and
rules reference.

How scoring works

Every rule has a severity, and each passing rule contributes its weight to the score:

The final score is reported as earned/maximum — higher means better MCP compliance.

Features

• Multiple transports: STDIO (local servers), Streamable HTTP, and SSE (remote servers)
• Auto-detection: Picks the right transport automatically — tries Streamable HTTP first, falls back to SSE for URLs
• Real handshake verification: A connection only counts once the server completes the MCP initialize handshake — pointing it at a non-MCP endpoint fails cleanly
• Multi-language: Audits both Python (.py) and Node.js (.js) MCP servers via STDIO
• Severity-based reporting: Rules categorized as CRITICAL, HIGH, MEDIUM, or LOW
• Library-friendly: Fully typed (py.typed); use MCPClient + MCPAuditor programmatically

What it audits

• Protocol Version Compliance:

  • ✅ Allowed versions check (CRITICAL)
  • ✅ Latest version recommendation (MEDIUM)
  • ✅ Deprecated version detection (HIGH)

• Server Information:

  • ✅ Server name presence (CRITICAL)
  • ✅ Server title presence (MEDIUM)
  • ✅ Server version presence (HIGH)

• Capabilities: Tools, resources, prompts, logging, and subscription support

• Tools: Names (presence, uniqueness, format), titles, descriptions, and JSON Schema validity of input/output schemas

• Security:

  • ✅ HTTPS/TLS usage with the actually negotiated TLS version
  • ✅ Valid certificate checks
  • ✅ Error responses checked for data leaks

• Transport:

  • ✅ Streamable HTTP usage (the current MCP standard; SSE-only servers get migration advice)

Requirements

• Python 3.11+
• Node.js on PATH if auditing a Node.js MCP server
• A Python interpreter on PATH if auditing a Python MCP server

Installation

pip install mcpscore

Or with uv:

uv tool install mcpscore

Quick start

Run mcpscore against any MCP server — local script or remote URL. The transport is detected automatically.

# Local Python MCP server (STDIO)
mcpscore path/to/your/server.py

# Local Node.js MCP server (STDIO)
mcpscore path/to/your/server.js

# Remote MCP server (auto-detects Streamable HTTP or SSE)
mcpscore https://example.com/mcp

# Machine-readable report for CI pipelines and tooling
mcpscore path/to/your/server.py --json > report.json

Example output

Welcome to MCPScore!
Connected to the MCP server: /path/to/server.py
Transport: stdio
Starting the audit...
✅ Protocol version '2025-11-25' is one of the allowed versions
✅ Protocol version '2025-11-25' is not deprecated
✅ Protocol version '2025-11-25' is the latest version
✅ Server name is present: 'weather'
✅ Server version is present: '1.17.0'
❌ Server title is not present in server info
✅ Tools capability is present
❌ listChanged is not supported by Tools
✅ Prompts capability is present
❌ listChanged is not supported by Prompts
✅ Resources capability is present
❌ listChanged is not supported by Resources
❌ subscribe is not supported by Resources
❌ Logging is not present in capabilities
✅ MCP Server provides at least one tool
✅ All Tools have a Name property specified
✅ All Tools have a Title property specified
✅ All Tools have a Description property specified
✅ All Tools have a valid Input Schema
✅ All Tools have a valid Output Schema
Audit finished. Final score: 55/71

JSON output

With --json, a machine-readable report is written to stdout (all log
output goes to stderr, so the JSON can be piped or redirected cleanly):

{
  "schema_version": 1,
  "mcpscore_version": "0.7.0",
  "generated_at": "2026-06-10T10:42:22+00:00",
  "target": "/path/to/server.py",
  "transport": "stdio",
  "score": 73,
  "max_score": 89,
  "summary": {
    "total": 26,
    "passed": 20,
    "failed": 6,
    "by_severity": {
      "CRITICAL": { "total": 9, "passed": 9, "failed": 0 },
      "HIGH": { "total": 11, "passed": 7, "failed": 4 },
      "MEDIUM": { "total": 5, "passed": 3, "failed": 2 },
      "LOW": { "total": 1, "passed": 1, "failed": 0 }
    }
  },
  "results": [
    {
      "rule_id": "protocol_version_allowed",
      "rule_name": "MCP Protocol Version - Allowed Versions",
      "severity": "CRITICAL",
      "severity_value": 5,
      "passed": true,
      "message": "✅ Protocol version '2025-11-25' is one of the allowed versions",
      "details": { "version": "2025-11-25" }
    }
  ]
}

rule_id values are stable identifiers intended for machine consumers
(snapshots, dashboards); display names and messages may change between
releases.

Troubleshooting

Connection fails

• Check the path or URL is correct and reachable
• For local servers, make sure Python or Node.js is on PATH
• "Not a valid MCP server (handshake failed)" means the endpoint responded but did not complete the MCP initialize handshake — verify the URL points at an actual MCP endpoint (often /mcp)

Protocol version errors

• Confirm your server uses a currently supported MCP protocol version
• If your server uses a newer version that MCPScore doesn't yet recognize, please open an issue

Contributing

See CONTRIBUTING.md for development setup and how to add audit rules. Why this project exists: MISSION.md. Security reports: SECURITY.md. Release history: CHANGELOG.md.

Feedback

Bug reports, feature requests, and general feedback are welcome at https://github.com/mcp-box/mcpscore/issues.

License

MIT — see LICENSE.