Creates a development branch with migrations from production branch.
AI agents use create_branch to create or update resources in PostgREST — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your PostgREST environment.
This tool performs a creation operation that reversibly adds a new branch entity to the system. While it involves branching logic and migrations, the core action is creating/writing new data structures rather than executing arbitrary code, deleting data, or moving money.
From the tool's definition Tool description states 'Creates a development branch' — a create operation that modifies database or project state by adding a new branch artifact with migrations.
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 PostgREST, 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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Creates a development branch with migrations from production branch. It is categorised as a Write tool in the PostgREST MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the PostgREST 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 PostgREST. 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 PostgREST MCP server (supabase/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 32 PostgREST tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
32 PostgREST tools catalogued and risk-classified — across an index of 42,500+ MCP servers.