update_comment · MCP Linear App MCP: Risk & Policy

WHAT IT DOES

What update_comment does on MCP Linear App

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

WHY IT NEEDS A POLICY

Why update_comment needs a policy

This tool modifies existing comments, which is a Write operation. While the description mentions deletion capability (which would be Destructive), the tool's name and primary framing ('update_comment') suggests the main use case is modification rather than deletion.

From the tool's definition Tool description states 'updates or deletes an existing comment' — the update operation is reversible (Write), but the deletion capability is irreversible (Destructive).

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_comment Rate-limited

update_comment 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": {
    "update_comment": {
      "limits": [
        {
          "counter": "update_comment_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 MCP Linear App, so you can run agents against it safely.

FAQ

Questions about update_comment

What does the update_comment tool do? +

A tool that updates or deletes an existing comment on an issue in Linear. It is categorised as a Write tool in the MCP Linear App MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on update_comment? +

Register the MCP Linear App MCP server in PolicyLayer and add a rule for update_comment: 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 MCP Linear App. Nothing to install.

What risk level is update_comment? +

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

Can I rate-limit update_comment? +

Yes. Add a rate_limit block to the update_comment 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 update_comment completely? +

Set action: deny in the PolicyLayer policy for update_comment. 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 update_comment? +

update_comment is provided by the MCP Linear App MCP server (zalab-inc/mcp-linear-app). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.