Add edit tools to MCP server

[samuelstevens]

Description

I want to use Claude Code in my terminal to create/edit Marimo notebooks. Because the MCP server does not expose edit_notebook or run_stale_cells, this doesn't work.

This statement in the docs tells me this is the case, but doesn't explain why:

These tools are only available when using the chat panel in agent mode. They are not exposed through the MCP server.

Suggested solution

Add them to the MCP server.

Are you willing to submit a PR?

• Yes

Alternatives

No response

Additional context

No response

[Light2Dark]

Thanks for the request, usually Claude Code can update the notebook's contents directly. Does that work? We are considering exposing some of those tools to MCP.

[samuelstevens]

No, run_stale_cells is super necessary so that Claude Code can iterate on the state of the notebook. Otherwise I have to run the cells myself, breaking the agent loop.

[mscolnick]

@samuelstevens you might find this config useful:

By default, when an agent modifies your notebook, cells are marked as stale instead of running automatically. To have cells run automatically when the agent saves changes, add this configuration to your pyproject.toml:

[tool.marimo.runtime]
watcher_on_save = "autorun"

This provides a more seamless experience when working with agents, as you'll see results immediately after the agent makes changes.

Link

[samuelstevens]

So the expected workflow with claude code is to use MCP and the watcher_on_save setting, then expect Claude Code to use get_cell_runtime_data and get_cell_outputs to see the updated cells?

[mscolnick]

Thats is the best way today to have Claude work iteratively without a human in the loop. But please let us know if you have feedback for what is missing or can be improved.

[samuelstevens]

This didn't work for me because the marimo server is running on a headless compute node. When I connect claude code, it can't authenticate. I get a picture like this:

Pressing authenticate flashes to "opening browser" then straight back to this, because there is no browser installed. Do you have any recommendations? I typically set up an ssh tunnel from this compute node to my laptop, then browse localhost:2723 on my laptop browser and use marimo normally.

[mscolnick]

Im not sure where this authentication error is coming from, so my suggestion could be incorrect, but you may want to try --no-token in the CLI to disable auth (assuming you are running in your own/trusted environment)

[samuelstevens]

Same problem. I also don't know where this authentication error comes from. Is there a log file I can provide to you to help?

[samuelstevens]

I am seeing this line repeated in the logs from uv run marimo --watch --port 2723 --no-token:

[W 251230 16:33:27 middleware:148] Received request with no server token (skew protection token). This could mean the header is being stripped by a proxy. If you are running behind a proxy, please ensure the header 'Marimo-Server-Token' is being forwarded.

[mscolnick]

Oh you need to run with --mcp to enable the MCP endpoints

[samuelstevens]

That worked. I still have auth errors, but it seems like it's not necessary.

[samuelstevens]

Actually I would like a tool that lets MCP clients re-run a particular cell. While the autowatch is nice, some of my cells depend on stuff on disk. Claude Code will run a script, get new results on disk, and then I want it to re-run a cell in the running notebook. I could tell it to make an arbitrary change to that cell, but that feels like a bad hack.