update_pull_request_branch

THE RISK

Medium Risk

Why update_pull_request_branch needs a policy

This tool modifies a pull request branch by incorporating changes from the base branch. While reversible (the original state can be recovered via git history or by rebasing again), it constitutes a Write operation rather than Read (it changes state) or Execute (it's a specific domain operation, not arbitrary code execution). It is not Destructive because the change is reversible and no data is permanently deleted.

From the tool's definition The tool description explicitly states it 'Update[s] a pull request branch', which modifies the state of a pull request by rebasing or merging the base branch into it. This is a write operation that changes existing data (the PR branch) reversibly.

Documented attack patterns abuse exactly the kind of access update_pull_request_branch gives an agent:

POLICY

How to control update_pull_request_branch

PolicyLayer is an MCP gateway — it sits between your AI agents and MCP-Brave-Search, and nothing reaches the server without passing your rules. This is the rule we recommend for update_pull_request_branch:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "update_pull_request_branch": {
      "limits": [
        {
          "counter": "update_pull_request_branch_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

update_pull_request_branch 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.

Create a free account and register MCP-Brave-Search — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

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EXPLORE

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FAQ

Questions about update_pull_request_branch

What does the update_pull_request_branch tool do? +

Update a pull request branch with the latest changes from the base branch. It is categorised as a Write tool in the MCP-Brave-Search 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_pull_request_branch? +

Register the MCP-Brave-Search MCP server in PolicyLayer and add a rule for update_pull_request_branch: 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-Brave-Search. Nothing to install.

What risk level is update_pull_request_branch? +

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

Can I rate-limit update_pull_request_branch? +

Yes. Add a rate_limit block to the update_pull_request_branch 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_pull_request_branch completely? +

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

update_pull_request_branch is provided by the MCP-Brave-Search MCP server (modelcontextprotocol/servers-archived). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every MCP-Brave-Search tool call.

Start from MCP-Brave-Search, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

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