Grade MCP servers A to F with the open behavioral litmus. npm: full toolset; hosted: lookups only.
Listed on
- Official MCP Registry
- Glamavia MCP Toplist
- PulseMCPvia MCP Toplist
First seen 2 Oct 2026. One server, whatever directories list it: each directory listing keeps its own page and history.
3
Directories
2 via MCP Toplist
3
Tools
From an anonymous probe
D
ToolBench grade
Arcade’s grade, not ours
8
GitHub stars
From MCP Toplist
Tools
| Tool | Description | Behaviour |
|---|---|---|
| check_server | 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. | Read-only |
| list_servers | 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`, `limit`, or `offset`. | Read-only |
| request_grade | 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>. | Changes data |
| Directory | Listing | Tier | First seen |
|---|---|---|---|
| Official MCP Registry | io.github.polygraphso/litmus | - | 2 Oct 2026 |
| Glama | Listed there according to MCP Toplist’s dataset; not collected by InvokeRank. | ||
| PulseMCP | Listed there according to MCP Toplist’s dataset; not collected by InvokeRank. | ||