update_pull_request_branch · Server Github MCP

WHAT IT DOES

What update_pull_request_branch does on Server Github

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

PARAMETERS

Parameter	Type	Required	Description
`repo`	string	Yes	Repository name
`owner`	string	Yes	Repository owner (username or organization)
`pull_number`	number	Yes	Pull request number
`expected_head_sha`	string	—	The expected SHA of the pull request's HEAD ref

Parameters from the server's own tool schema.

WHY IT NEEDS A POLICY

Why update_pull_request_branch needs a policy

This tool merges/rebases the base branch into the PR branch, modifying the PR branch's commit history. This is a reversible write operation (the branch can be reset), not destructive. Misuse could introduce unwanted changes into a PR branch, but the blast radius is moderate since it's scoped to a specific PR branch.

From the tool's definition Update a pull request branch with the latest changes from the base branch

Attacks that exploit this kind of access

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 Server Github MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

What parameters does update_pull_request_branch accept? +

update_pull_request_branch accepts 4 parameters: repo, owner, pull_number, expected_head_sha. Required: repo, owner, pull_number. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on update_pull_request_branch? +

Register the Server Github 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 Server Github. 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 Server Github MCP server (@iflow-mcp/server-github). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.