update_entry · MCP Auth MCP: Risk & Policy

WHAT IT DOES

What update_entry does on MCP Auth

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

WHY IT NEEDS A POLICY

Why update_entry needs a policy

This tool modifies data (a journal entry) in a reversible manner. The update operation does not delete or destroy data (which would be Destructive), nor does it execute arbitrary code (which would be Execute). It is a standard Write operation that changes existing data.

From the tool's definition Tool name is 'update_entry' and description states it 'Update[s] a journal entry' with selective field updates based on what is provided.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_entry Rate-limited

update_entry 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_entry": {
      "limits": [
        {
          "counter": "update_entry_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 Auth, so you can run agents against it safely.

FAQ

Questions about update_entry

What does the update_entry tool do? +

Update a journal entry. Fields that are not provided (or set to undefined) will not be updated. Fields that are set to null or any other value will be updated. It is categorised as a Write tool in the MCP Auth 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_entry? +

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

What risk level is update_entry? +

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

Can I rate-limit update_entry? +

Yes. Add a rate_limit block to the update_entry 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_entry completely? +

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

update_entry is provided by the MCP Auth MCP server (rubenpenap/mcp-auth). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.