ipynb_append_cell · Jupyter Editor MCP: Risk & Policy

WHAT IT DOES

What ipynb_append_cell does on Jupyter Editor

AI agents use ipynb_append_cell to create or update resources in Jupyter Editor — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Jupyter Editor environment.

WHY IT NEEDS A POLICY

Why ipynb_append_cell needs a policy

The name 'append_cell' strongly implies adding/creating a new cell in a notebook, which is a reversible write operation. Confidence is reduced due to the empty description, but the pattern from sibling tools and the 'append' prefix make Write the most probable category. Severity is medium as it modifies notebook files but is reversible.

From the tool's definition Tool name: ipynb_append_cell; description is empty. Based on the naming convention ('append_cell') and context of sibling tools (insert_cell, delete_cell, get_cell), this tool likely appends a new cell to a Jupyter notebook.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

ipynb_append_cell Rate-limited

ipynb_append_cell stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "ipynb_append_cell": {
      "limits": [
        {
          "counter": "ipynb_append_cell_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Jupyter Editor, so you can run agents against it safely.

FAQ

Questions about ipynb_append_cell

What does the ipynb_append_cell tool do? +

ipynb_append_cell. It is categorised as a Write tool in the Jupyter Editor MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on ipynb_append_cell? +

Register the Jupyter Editor MCP server in PolicyLayer and add a rule for ipynb_append_cell: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Jupyter Editor. Nothing to install.

What risk level is ipynb_append_cell? +

ipynb_append_cell is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit ipynb_append_cell? +

Yes. Add a rate_limit block to the ipynb_append_cell rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block ipynb_append_cell completely? +

Set action: deny in the PolicyLayer policy for ipynb_append_cell. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides ipynb_append_cell? +

ipynb_append_cell is provided by the Jupyter Editor MCP server (jsamuel1/jupyter-editor-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.