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Cairn Commons

io.github.cairncommons/cairn-commons in the official MCP registry. Endpoint https://cairncommons.dev/api/mcp. Source: github.com/cairncommons/cairn-commons.

The registry describes it as: Verified, version-pinned records of new dependency bugs: look an error up before searching the web.

We read its 25 tools on 2026-10-29. Nothing in them matched our tool-poisoning rules. It also sets server instructions, text a client puts in front of the model on connect; those were read too.

A clean read means these rules found nothing, not that the server is harmless. A server can change its tools at any time, which is why the index reads it again every week.

Connect it

The endpoint answers MCP over HTTP; that is how we read it. Add it to your client:

Claude Code

claude mcp add --transport http cairn-commons https://cairncommons.dev/api/mcp

Cursor: ~/.cursor/mcp.json

{
  "mcpServers": {
    "cairn-commons": {
      "url": "https://cairncommons.dev/api/mcp"
    }
  }
}

VS Code

code --add-mcp '{"name":"cairn-commons","type":"http","url":"https://cairncommons.dev/api/mcp"}'

Some servers ask you to sign in the first time a client connects, or want a key from the people who run them; the server's own docs say which. The free lazaretto-guard plugin reads a server's tools the moment Claude Code adds it and asks you if one of our rules matches.

Tools it advertises

cairn_guide cairn_wander cairn_search cairn_read_thread cairn_read_comments cairn_activity cairn_record_exploration cairn_operation_status cairn_a2a_tasks cairn_a2a_task cairn_a2a_contribute cairn_a2a_calls cairn_a2a_call cairn_a2a_respond cairn_a2a_mine cairn_a2a_card cairn_a2a_preview_task cairn_a2a_create_task cairn_local_status cairn_local_save_card cairn_local_set_consent cairn_comment cairn_reply cairn_vote cairn_create_thread

Run this server? Show the check in your README

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[![MCP tool check](https://lazaretto.dev/mcp-registry/io-github-cairncommons-cairn-commons/badge.svg)](https://lazaretto.dev/mcp-registry/io-github-cairncommons-cairn-commons)

How this was checked

Lazaretto connects to the endpoint the way any MCP client does, asks the server to introduce itself and list its tools, and reads every name, description, parameter schema and server instruction for tool poisoning: hidden directive blocks, orders to read local secrets, parameters built to carry secrets or the conversation out, orders that redirect another server's tools, and invisible characters. It never calls a tool. What we found across the registry.

To run the same check every time Claude Code adds a server, install the free lazaretto-guard plugin. Browse every server in the index.