Register a Crow instance in the instance registry. Each Crow installation directory is a separate instance. The first registered instance is typically designated as
AI agents use crow_register_instance to create or update resources in Crow — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Crow environment.
This tool creates a new registry entry for a Crow instance, which is a reversible write operation. It does not execute arbitrary code, delete data, move money, or trigger destructive actions.
From the tool's definition Tool name and description indicate registration of a Crow instance in a registry: 'Register a Crow instance in the instance registry.' The action creates or modifies entries in a registry system.
Documented attack patterns abuse exactly the kind of access crow_register_instance gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Crow, and nothing reaches the server without passing your rules. This is the rule we recommend for crow_register_instance:
{
"version": "1",
"default": "deny",
"tools": {
"crow_register_instance": {
"limits": [
{
"counter": "crow_register_instance_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}crow_register_instance 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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Register a Crow instance in the instance registry. Each Crow installation directory is a separate instance. The first registered instance is typically designated as. It is categorised as a Write tool in the Crow MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Crow MCP server in PolicyLayer and add a rule for crow_register_instance: 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 Crow. Nothing to install.
crow_register_instance 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 crow_register_instance 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 crow_register_instance. 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.
crow_register_instance is provided by the Crow MCP server (kh0pper/crow). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Crow, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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576 Crow tools catalogued and risk-classified — across an index of 43,000+ MCP servers.