unlock_file · Todos MCP: Risk & Policy

WHAT IT DOES

What unlock_file does on Todos

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

WHY IT NEEDS A POLICY

Why unlock_file needs a policy

Unlocking a file modifies system state (lock status) reversibly, which qualifies as Write rather than Read. It is not Destructive because no data is deleted or irrevocably lost. While it could affect concurrent access if abused, the blast radius is limited to lock management rather than data loss or financial impact.

From the tool's definition Tool name 'unlock_file' and description 'Release a file lock' indicate a state-changing operation that modifies lock metadata without deleting data. The operation is reversible (the file can be locked again).

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

unlock_file Rate-limited

unlock_file 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": {
    "unlock_file": {
      "limits": [
        {
          "counter": "unlock_file_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 Todos, so you can run agents against it safely.

FAQ

Questions about unlock_file

What does the unlock_file tool do? +

Release a file lock. Only the lock holder can release it. Returns true if released. It is categorised as a Write tool in the Todos MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on unlock_file? +

Register the Todos MCP server in PolicyLayer and add a rule for unlock_file: 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 Todos. Nothing to install.

What risk level is unlock_file? +

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

Can I rate-limit unlock_file? +

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

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

unlock_file is provided by the Todos MCP server (@hasna/todos). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.