langchain-arcnm

Manufacturing should-cost from a CAD file, for your LangChain agent.

ARCNM turns a STEP file into an itemised manufacturing cost for machined and sheet-metal parts: unit cost, setup cost, cycle time, and the cost sheet behind them. This package gives a LangChain or LangGraph agent the ARCNM REST API as tools, so it can price a part, explain what drives the cost, and compare lot sizes.

pip install -U langchain-arcnm

Setup

1. In ARCNM, open Settings, then API keys, then New key. ARCNM shows the key once.
2. Export it:

export ARCNM_API_KEY="..."

Reads need the parts:read scope. Starting or cancelling a calculation needs parts:write. The Free plan includes 10 calculations a month, no card required.

Use it in an agent

from langchain.agents import create_agent
from langchain_arcnm import ArcnmToolkit

agent = create_agent(
    "anthropic:claude-sonnet-5-5",
    tools=ArcnmToolkit(root_dir="./cad").get_tools(),
)
result = agent.invoke(
    {
        "messages": [
            {
                "role": "user",
                "content": "What does bracket.step cost at a lot of 50, and what drives it?",
            }
        ]
    }
)
print(result["messages"][-1].content)

Call a tool directly

from langchain_arcnm import UploadAndQuoteTool

quote = UploadAndQuoteTool()
print(quote.invoke({"file_path": "bracket.step", "lot_size": 50}))

Every tool returns JSON as a string. An API error comes back as the tool result, with its stable error code and request id, so the agent can react to it; set handle_tool_error=False to have it raised instead.

Tools

The names match the ARCNM MCP server, so an agent sees the same verbs on either surface.

upload_and_quote, quote_part and get_calculation with wait=true wait up to wait_timeout seconds (default 120) for the result. A calculation still running after that comes back with its id, and the agent can ask again with get_calculation.

Configuration

Pass these to ArcnmToolkit or to any single tool.

Security

upload_and_quote reads the file path the model gives it and sends that file to ARCNM. Set root_dir so it can only read the folder you meant, and use read_only=True for an agent that should never start a calculation. A key with only parts:read cannot start one either.

Development

uv sync --all-groups
make test              # unit tests, no network
make integration_test  # against the live API; needs ARCNM_API_KEY, uses no calculations
make lint

make integration_test BILLABLE=1 also quotes tests/integration_tests/shaft_thread.step, which uses one calculation.

arcnm-contract.json lists every ARCNM operation and field this package relies on. ARCNM checks it against every change to its API before that change merges. It is not part of the published package.

Links

• ARCNM docs
• ARCNM API examples
• LangChain tools

License

MIT