MCP server

Litmus

io.github.polygraphso/litmus

Checked 26 Oct 2026, 08:29 UTC · Connected to it and listed its tools

Grade MCP servers A to F with the open behavioral litmus. npm: full toolset; hosted: lookups only.

Website Source

At a glance

Type

MCP server

Publisher

Not verified

Status

Working at last check

Tools

3

Token cost

About 646 tokens per request

Sets up in

Claude Code, Claude Desktop, Codex, Gemini CLI, Cursor, VS Code, Antigravity, ChatGPT, OpenAI API, Grok

Last checked

26 Oct 2026, 08:29 UTC

Connect it to your agent

Add to CursorAdd to VS CodeVS Code Insiders

Opens the app, which shows the server and asks you to confirm. For other apps, copy the setup below.

Claude Code

claude mcp add --transport http litmus https://polygraph.so/api/mcp

Claude Desktop

Settings → Connectors → Add custom connector, and paste the URL.

Codex (config.toml)

[mcp_servers.litmus]
url = "https://polygraph.so/api/mcp"

Gemini CLI

{"mcpServers":{"litmus":{"httpUrl":"https://polygraph.so/api/mcp"}}}

Cursor

{"mcpServers":{"litmus":{"url":"https://polygraph.so/api/mcp"}}}

VS Code

{"servers":{"litmus":{"type":"http","url":"https://polygraph.so/api/mcp"}}}

Antigravity

agy mcp add litmus https://polygraph.so/api/mcp

ChatGPT

Settings → Apps & Connectors → Advanced settings: turn on Developer mode, then Create a connector and paste the URL. Which plans can do this varies.

OpenAI API (Responses tools)

{"type":"mcp","server_label":"litmus","server_url":"https://polygraph.so/api/mcp","require_approval":"always"}

Grok (xAI API tools)

{"type":"mcp","server_label":"litmus","server_url":"https://polygraph.so/api/mcp"}

Tools

• check_server ~204 tokens
  Read a server's published behavioral grade (A-F) from polygraph.so in under a second; no execution. The pre-flight check before recommending or installing an MCP server. On a miss it returns not_available (unevaluated: neither safe nor unsafe) with next steps.
• list_servers ~240 tokens
  Servers with a published polygraph grade, sorted A-first then by ref. Returns up to `limit` rows starting at `offset` (default limit 25, capped at 100 per call); `grade` restricts to one letter. `summary` always covers the full graded corpus (a total plus a count per grade), regardless of `grade`, `
• request_grade ~202 tokens
  Hosted grading is discontinued. This tool returns gone. Existing published grades remain available via check_server / list_servers. To grade a server yourself, run the open harness: npx -y -p @polygraphso/litmus polygraphso-litmus litmus <server_ref>.

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