pr.updateBranch · Promethean OS MCP: Risk & Policy

WHAT IT DOES

What pr.updateBranch does on Promethean OS MCP

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

WHY IT NEEDS A POLICY

Why pr.updateBranch needs a policy

This tool creates or modifies data (the branch state) reversibly through a merge operation. It is not destructive because the original branch history remains accessible (merges do not erase commits). It is not a simple read operation because it performs a side effect that alters repository state.

From the tool's definition The tool performs a server-side merge operation ('merge base→head') which modifies the state of a git branch.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

pr.updateBranch Rate-limited

pr.updateBranch 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": {
    "pr.updateBranch": {
      "limits": [
        {
          "counter": "pr.updatebranch_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 Promethean OS MCP, so you can run agents against it safely.

FAQ

Questions about pr.updateBranch

What does the pr.updateBranch tool do? +

Server-side merge base→head (like the Update branch button). It is categorised as a Write tool in the Promethean OS MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on pr.updateBranch? +

Register the Promethean OS MCP server in PolicyLayer and add a rule for pr.updateBranch: 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 Promethean OS MCP. Nothing to install.

What risk level is pr.updateBranch? +

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

Can I rate-limit pr.updateBranch? +

Yes. Add a rate_limit block to the pr.updateBranch 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 pr.updateBranch completely? +

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

pr.updateBranch is provided by the Promethean OS MCP server (octave-commons/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.