unpin_memory · Agent Bus MCP: Risk & Policy

WHAT IT DOES

What unpin_memory does on Agent Bus

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

WHY IT NEEDS A POLICY

Why unpin_memory needs a policy

This tool modifies the ordering/pinning state of a memory entry, reversing a pin operation. It changes metadata/state but does not delete data and is reversible (the memory can be re-pinned). This fits Write rather than Destructive. Blast radius is low as it only affects memory prioritization within the local agent bus.

From the tool's definition Unpin a memory so it returns to normal recent-memory ordering

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

unpin_memory Rate-limited

unpin_memory 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": {
    "unpin_memory": {
      "limits": [
        {
          "counter": "unpin_memory_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 Agent Bus, so you can run agents against it safely.

FAQ

Questions about unpin_memory

What does the unpin_memory tool do? +

Unpin a memory so it returns to normal recent-memory ordering. It is categorised as a Write tool in the Agent Bus MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on unpin_memory? +

Register the Agent Bus MCP server in PolicyLayer and add a rule for unpin_memory: 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 Agent Bus. Nothing to install.

What risk level is unpin_memory? +

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

Can I rate-limit unpin_memory? +

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

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

unpin_memory is provided by the Agent Bus MCP server (mustaphasteph/agent-bus). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.