Otter MCP — Engineering Intelligence Layer

Official Model Context Protocol stdio server. External AI agents (Cursor, Claude Desktop, Claude Code) get a repository brain: impact, architecture guard, verification, and approval-gated tasks.

Install (no monorepo clone)

pip install otter-mcp
# or: uv pip install otter-mcp

Or run without a permanent install:

uvx otter-mcp

Cursor / Claude (mcp.json)

{
  "mcpServers": {
    "otter": {
      "command": "uvx",
      "args": ["otter-mcp"],
      "env": {
        "OTTER_REPO_ROOT": "${workspaceFolder}"
      }
    }
  }
}

If you prefer pip’s console script:

{
  "mcpServers": {
    "otter": {
      "command": "otter-mcp",
      "env": {
        "OTTER_REPO_ROOT": "${workspaceFolder}"
      }
    }
  }
}

Optional API persistence

{
  "env": {
    "OTTER_REPO_ROOT": "${workspaceFolder}",
    "OTTER_API_URL": "http://127.0.0.1:8000",
    "OTTER_SESSION": "your-web-otter-session-cookie",
    "OTTER_REPOSITORY_ID": "imported-repo-id"
  }
}

Auth note: CLI otter login (GitHub) is not an API session. Export the Web/Docker otter_session cookie as OTTER_SESSION.

Requirements

• Python 3.11+
• A local checkout via OTTER_REPO_ROOT and/or an imported repo under REPOSITORY_DATA_DIR/{repository_id}
• Optional: running Otter API for memory / code-tasks

Tools

Writes never apply silently: otter_task_execute with apply returns approval_required until status is approved.

Resources & prompts

• Resources: otter://repo/overview, architecture, constitution, health, dependencies, otter://task/{id}…
• Prompts: otter-investigate, otter-plan, otter-review, otter-debug, otter-security-review, otter-architecture-review

Developer install (from this monorepo)

pip install -e apps/mcp
export OTTER_REPO_ROOT=/path/to/repo
otter-mcp

Security

• No general execute_shell tool — only allowlisted npm scripts / pytest / ruff
• Path traversal rejected on repository_id and relative paths
• Oversized tool JSON is truncated in responses

MCP Registry

Package metadata: server.json. Registry name: io.github.manasdutta04/otter.

See also: https://otter.manasdutta.com/docs/mcp