drive-mcp-handlers

Driving tool handlers directly

Every MCP tool is a plain async handler named _tool_<name> in src/cabineteer/server.py that takes an args dict and returns list[types.TextContent] whose [0].text is a JSON string. You can call these without any MCP client — this bypasses the transport entirely and always runs the current on-disk code, even when the session's registered cabinet server process is stale.

Pattern

import asyncio, json
from cabineteer import server as srv

res = asyncio.run(srv._tool_evaluate_cabinet({"width": 600, "height": 720, "depth": 550}))
print(json.loads(res[0].text)["summary"])   # {'errors': 0, 'warnings': 0, 'info': 0, 'pass': True}

Run it with uv run python - <<'EOF' ... EOF (or uv run python -c "...").

Handler names

The tool name usually maps to _tool_<name> — e.g. design_cabinet → _tool_design_cabinet, generate_cutlist → _tool_generate_cutlist, visualize_project → _tool_visualize_project. There are exceptions (e.g. list_joinery_options → _tool_list_joinery), so the eval harness's TOOL_DISPATCH (in evals/harness.py) is the canonical name→handler map — check it rather than assuming the pattern.

Args

The args dict mirrors the tool's inputSchema in server.py. Cabinet geometry uses drawer_config as a list of [height_mm, opening_type] pairs (e.g. [[300, "drawer"], [192, "drawer"]]); opening_type is one of drawer | door | door_pair | shelf | open. All units are millimetres.

Why this matters here

• Stale server: the session's cabinet server only picks up merged code after a /mcp reconnect. Direct-drive sidesteps that — use it to verify a fix landed before reconnecting.
• Reproducing evals: copy a scenario's args from evals/scenarios.py and drive the handler to see the full JSON result an assertion walked (evals only surface the failing path).
• File-writing tools write under ~/.cabineteer/. The visualize_* tools accept an explicit output_dir — point it at a scratch path when probing. generate_cutlist/generate_project_cutlist have no output_dir (they always write to ~/.cabineteer/cutlists/, and passing output_dir raises ValueError: Unknown cabinet parameter(s)); use a throwaway name if you want to avoid clobbering. Output name is validated as a filename stem (no ../separators) — a traversal name raises.