AI agents use create_branch to create or update resources in MCP-Brave-Search — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your MCP-Brave-Search environment.
This tool creates a new branch, which is a write operation that modifies the repository structure reversibly. Branches can be deleted, making this a non-destructive modification. The blast radius is limited—creating unwanted branches is a minor inconvenience compared to deleting data or executing arbitrary code. Severity is low because the impact is easily recoverable.
From the tool's definition Tool name is 'create_branch' with description 'Create a new branch in a GitHub repository'. Creating a branch is a reversible operation that modifies repository state by adding a new reference.
Documented attack patterns abuse exactly the kind of access create_branch gives an agent:
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 create_branch:
{
"version": "1",
"default": "deny",
"tools": {
"create_branch": {
"limits": [
{
"counter": "create_branch_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}create_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.
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Create a new branch in a GitHub repository. 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.
Register the MCP-Brave-Search MCP server in PolicyLayer and add a rule for create_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.
create_branch 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 create_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.
Set action: deny in the PolicyLayer policy for create_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.
create_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.
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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59 MCP-Brave-Search tools catalogued and risk-classified — across an index of 43,000+ MCP servers.