Opt in or out of contact discovery by setting your email hash. Other Crow users can then find you by email without revealing your actual address.
AI agents use crow_set_discoverable 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 modifies user-controlled privacy and discoverability settings by updating email hash state. It creates or changes data (email hash registration for discovery purposes) rather than retrieving it (Read), and the action is fully reversible—users can toggle on/off at will. While it has privacy implications, it is fundamentally a Write operation.
From the tool's definition Tool performs 'Opt in or out' and 'setting your email hash' - these are reversible modifications to user settings/preferences that control visibility and discoverability.
Documented attack patterns abuse exactly the kind of access crow_set_discoverable 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_set_discoverable:
{
"version": "1",
"default": "deny",
"tools": {
"crow_set_discoverable": {
"limits": [
{
"counter": "crow_set_discoverable_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}crow_set_discoverable 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.
Free to start. No card required.
Opt in or out of contact discovery by setting your email hash. Other Crow users can then find you by email without revealing your actual address. 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_set_discoverable: 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_set_discoverable 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_set_discoverable 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_set_discoverable. 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_set_discoverable 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.
Free to start. No card required.
576 Crow tools catalogued and risk-classified — across an index of 43,000+ MCP servers.