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Sextant

Use with Claude Code

The fastest way to use Sextant inside Claude Code is the bundled plugin — it registers the MCP server, three skills, three slash commands, and a sample git pre-commit hook in one go.

Section titled “Recommended: install the plugin”

From a Claude Code session:

/plugin marketplace add kylebastien/sextant-mcp
/plugin install sextant@kylebastien/sextant-mcp

The plugin lives at plugin/ in the sextant-mcp repo, so the marketplace is the repo itself. After installing, restart the session to pick up the hooks.

See the Claude Code plugin guide for what each piece does.

Manual MCP config

Section titled “Manual MCP config”

If you want only the MCP server (no hooks, no skills), add it to your project’s .mcp.json:

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

Or to your user-level Claude Code config (~/.claude/mcp.json on macOS and Linux). Restart the session after editing.

The server reads config from the current working directory’s repo root. If you run Claude Code from outside a repo, the server starts but finds no rules.

With LLM rules

Section titled “With LLM rules”
{
  "mcpServers": {
    "sextant": {
      "command": "sextant-mcp",
      "env": {
        "ANTHROPIC_API_KEY": "${ANTHROPIC_API_KEY}"
      }
    }
  }
}

Claude Code’s MCP env var substitution lets you pass through your shell’s API key without committing it.

Verify the server is running

Section titled “Verify the server is running”

In a Claude Code session, ask:

What MCP tools are available?

You should see grade_diff, grade_files, list_rules, explain_rule, get_config. If not, check Claude Code’s MCP log panel — sextant-mcp writes its own logs to stderr, which Claude Code surfaces.

See also

Section titled “See also”