Use with Claude Desktop

Claude Desktop discovers MCP servers via its config file. Add Sextant there once and the tools show up in every conversation.

1. Locate the config

OS	Path
macOS	`~/Library/Application Support/Claude/claude_desktop_config.json`
Windows	`%APPDATA%\Claude\claude_desktop_config.json`
Linux	`~/.config/Claude/claude_desktop_config.json`

Create the file if it doesn’t exist.

2. Add the server

{
  "mcpServers": {
    "sextant": {
      "command": "sextant-mcp"
    }
  }
}

If sextant-mcp is not on the global PATH (Claude Desktop launches servers without a login shell), use an absolute path:

{
  "mcpServers": {
    "sextant": {
      "command": "/Users/you/.cargo/bin/sextant-mcp"
    }
  }
}

3. Wire LLM rules (optional)

If you use rules with evaluator.type: llm, pass the API key through to the server. Claude Desktop doesn’t inherit your shell environment, so the env block is the supported way:

{
  "mcpServers": {
    "sextant": {
      "command": "/Users/you/.cargo/bin/sextant-mcp",
      "env": {
        "ANTHROPIC_API_KEY": "sk-ant-api03-..."
      }
    }
  }
}

Treat this file as a secret — it sits in plaintext on disk.

4. Working directory

Claude Desktop runs MCP servers in your home directory by default. The server looks for .sextant/config.toml in the repo root of its CWD, so for repo-aware grading you’ll want to launch Claude Desktop from the project root, or set cwd explicitly:

{
  "mcpServers": {
    "sextant": {
      "command": "/Users/you/.cargo/bin/sextant-mcp",
      "cwd": "/Users/you/code/your-repo"
    }
  }
}

For multi-repo workflows, the Claude Code plugin is a better fit — it picks up the repo of whichever session you’ve launched.

5. Restart Claude Desktop

The MCP config is loaded at startup. Quit and reopen the app to pick up changes.

Verify

Ask in a conversation:

What MCP tools do you have?

You should see all five Sextant tools listed. If not, check Claude Desktop’s developer logs — server stderr is forwarded there.