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LemonCrow MCP

LemonCrow's MCP server is the host-neutral transport for context retrieval, rescue, trace recording, rubric gates, memory, and code-aware helper tools.

Start Modes​

Installed product​

lc mcp

Source checkout​

cd lemoncrow
uv run lc mcp

Remote service-backed mode​

Set LEMONCROW_SERVICE_URL (plus LEMONCROW_API_KEY if the service requires auth) to route the supported core calls through the HTTP service. Remote mode is enabled whenever LEMONCROW_SERVICE_URL is set; unset it to run fully local.

Active vs. Passive Mode​

LemonCrow distinguishes between developer mode and passive compatibility mode.

  • With LEMONCROW_DEV_MODE=1, the stdio MCP server exposes the full active tool surface.
  • Without developer mode, record remains active and the host may still see some compatibility tools as passive noop surfaces, but context/retrieval/edit workflows are intentionally not active.
  • Older host templates may use previous-generation tool names; the list below is the current public stdio MCP surface.

Active Tool Names​

With LEMONCROW_DEV_MODE=1, the current stdio MCP registry exposes these tool names:

  • context
  • route
  • rescue
  • trace
  • verify
  • memory
  • read
  • edit
  • sql
  • search
  • compact
  • code
  • bash

Structured Tool Operations​

  • memory uses an op field such as block_upsert, block_get, archive, and recall.
  • compact uses op=output, op=session, or op=advise.
  • route uses op=decide and op=verify.
  • code uses op=index, op=search, op=blame, op=hover, op=symbol, op=outline, op=files, op=explore, op=routes, op=status, op=context, op=pattern, op=rename, op=cache_status, or op=cache_invalidate. (Call-graph and reference relations — callers, callees, usages — are returned folded into op=explore.)

Remote Mode Coverage​

In remote MCP mode, LemonCrow currently forwards the core service-backed flows for:

  • context retrieval via /v1/reasoning/context
  • rescue via /v1/reasoning/rescue
  • rubric evaluation via /v1/rubrics/run
  • trace recording via /v1/traces
  • memory block/archive/recall operations via /v1/memory/*

Host Example​

Installed-product config:

{
  "mcpServers": {
    "lc": {
      "command": "lc mcp",
      "env": {
        "LEMONCROW_ROOT": "~/.lemoncrow",
        "LEMONCROW_WORKSPACE_ROOT": "."
      }
    }
  }
}

Source-checkout config:

{
  "mcpServers": {
    "lc": {
      "command": "uv",
      "args": ["run", "lc mcp"],
      "cwd": "/abs/path/to/lemoncrow",
      "env": {
        "LEMONCROW_ROOT": "~/.lemoncrow",
        "LEMONCROW_WORKSPACE_ROOT": "."
      }
    }
  }
}

Embedding via SDK​

When you want the MCP contract in-process, use LemonCrowClient.mcp() from the Python SDK. It mirrors the same tool semantics and dev-mode gating rules as the stdio server.