Cells

edit_cell_source

Perform a surgical find-and-replace within a cell's source (like an editor's Edit tool).

Perform a surgical find-and-replace within a cell's source (like an editor's Edit tool). Finds old_string in the cell and replaces it with new_string. Matching is literal (not regex) and may span multiple lines. By default, old_string must appear exactly once; set replace_all=True for multiple occurrences. Returns a diff of the changes made.

Prefer this over overwrite_cell_source for small, targeted edits — it is safer because unchanged parts of the cell are left untouched. Use read_cell first to see the current source and construct an accurate old_string.

destructive: yes

Parameters

ParameterTypeRequiredDefaultDescription
cell_indexintegeryes—Index of the cell to edit (0-based)
old_stringstringyes—Exact string to find in cell source
new_stringstringyes—Replacement string
replace_allbooleannofalseReplace all occurrences (default: first only)
notebook_namestring | nullnonullTarget this specific connected notebook instead of the currently activated one. Use when multiple clients share this server, to avoid racing the shared 'current notebook' pointer. Omit to use the currently activated notebook.

Output

{
  "properties": {
    "result": {
      "description": "Success message with diff showing changes made",
      "title": "Result",
      "type": "string"
    }
  },
  "required": [
    "result"
  ],
  "title": "edit_cell_sourceOutput",
  "type": "object"
}

Call it

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "edit_cell_source",
    "arguments": {
      "cell_index": 0,
      "old_string": "<old_string>",
      "new_string": "<new_string>",
      "replace_all": false,
      "notebook_name": null
    }
  }
}
result = await session.call_tool("edit_cell_source", arguments={"cell_index": 0, "old_string": "<old_string>", "new_string": "<new_string>", "replace_all": False, "notebook_name": None})

Source

Registered by the @mcp.tool decorator on edit_cell_source in jupyter_mcp_server/server.py.

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