topic_update · HashPilot MCP: Risk & Policy

WHAT IT DOES

What topic_update does on HashPilot

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

WHY IT NEEDS A POLICY

Why topic_update needs a policy

This tool modifies existing blockchain state (HCS topic properties) but does not delete or destroy data, and involves no financial transactions. It requires administrative privileges ('Requires admin key') which limits blast radius but the change affects a shared consensus topic that other parties may depend on.

From the tool's definition Tool name 'topic_update' and description 'Update an existing HCS topic' indicates modification of blockchain data. Can 'update memo and auto-renew period' on Hedera Consensus Service topics, which are reversible changes to topic metadata.

Risk signalsAdmin/system-level operation

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

topic_update Rate-limited

topic_update 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": {
    "topic_update": {
      "limits": [
        {
          "counter": "topic_update_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 HashPilot, so you can run agents against it safely.

FAQ

Questions about topic_update

What does the topic_update tool do? +

Update an existing HCS topic. Requires admin key to be set on the topic during creation. Can update memo and auto-renew period. It is categorised as a Write tool in the HashPilot MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on topic_update? +

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

What risk level is topic_update? +

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

Can I rate-limit topic_update? +

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

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

topic_update is provided by the HashPilot MCP server (justmert/hashpilot). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.