checkout
Switches branches or restores files. Returns structured data with ref, previous ref, whether a new branch was created, and detached HEAD status. Pass
This record as markdown: /tools/io-github-dave-london-github/checkout.md
What checkout does on Github
AI agents use checkout to create or update resources in Github, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Github environment.
Why checkout is rated Medium
The checkout operation modifies repository state by switching branches or restoring file contents. This is reversible (you can checkout another branch or restore different versions), so it qualifies as Write rather than Destructive. The medium severity reflects that branch switching and file restoration can affect repository state and subsequent operations, but the effects are not irreversible or destructive.
From the tool's definition Tool description states it 'Switches branches or restores files', which are write operations that modify the working state of a repository. Restoring files involves modifying repository contents.
Attacks that exploit this kind of access
The rule that runs checkout safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Github, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For checkout, this is the rule to start with:
checkout 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.
The button opens the PolicyLayer dashboard: create your workspace, connect Github, apply this rule, and every checkout call is checked against it from then on.
Questions about checkout
Switches branches or restores files. Returns structured data with ref, previous ref, whether a new branch was created, and detached HEAD status. Pass. It is categorised as a Write tool in the Github MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Github MCP server in PolicyLayer and add a rule for checkout: 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 Github. Nothing to install.
checkout is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the checkout 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.
Set action: deny in the PolicyLayer policy for checkout. 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.
checkout is provided by the Github MCP server (@paretools/github). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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