// MCP TOOL REFERENCE

mastodon_defederate

Instance-wide defederation — admin-only. Uses the admin/domain_blocks endpoint with severity=suspend. QUEUED — requires operator confirmation in the Nest panel before firing.

ServerCrow
CategoryDestructive

How to control mastodon_defederate ↓

WHAT IT DOES

What mastodon_defederate does on Crow

AI agents call mastodon_defederate to permanently remove resources in Crow — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.

THE RISK

Critical Risk

Why mastodon_defederate needs a policy

Defederating (suspending) an entire instance is an irreversible administrative action that severs all connections with a remote Mastodon instance, destroying federated relationships, blocking all users from that instance, and removing existing content. 'severity=suspend' is the most extreme domain block level.

From the tool's definition defederate ... severity=suspend ... Instance-wide defederation — admin-only

Risk signalsAdmin/system-level operation

Documented attack patterns abuse exactly the kind of access mastodon_defederate gives an agent:

POLICY

How to control mastodon_defederate

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 mastodon_defederate:

policy.json

{
  "version": "1",
  "default": "deny",
  "hide": [
    "mastodon_defederate"
  ]
}

mastodon_defederate disappears from the agent's tool list entirely, and any attempt to call it is denied. The rest of the server keeps working.

Create a free account and register Crow — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

RESTRICT THIS TOOL →

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EXPLORE

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Go deeper

Critical-risk tools in Crow → Every critical-risk tool this server exposes, in one view.
All critical-risk MCP tools → Every critical-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Blast radius → How much damage one compromised or confused agent can do — and how to bound it.
Tool call approval → Approval gates on individual tool calls: auto-allow, prompt, or deny.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about mastodon_defederate

What does the mastodon_defederate tool do? +

Instance-wide defederation — admin-only. Uses the admin/domain_blocks endpoint with severity=suspend. QUEUED — requires operator confirmation in the Nest panel before firing. It is categorised as a Destructive tool in the Crow MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.

How do I enforce a policy on mastodon_defederate? +

Register the Crow MCP server in PolicyLayer and add a rule for mastodon_defederate: 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.

What risk level is mastodon_defederate? +

mastodon_defederate is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.

Can I rate-limit mastodon_defederate? +

Yes. Add a rate_limit block to the mastodon_defederate 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.

How do I block mastodon_defederate completely? +

Set action: deny in the PolicyLayer policy for mastodon_defederate. 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.

What MCP server provides mastodon_defederate? +

mastodon_defederate 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.

Enforce policy on every Crow tool call.

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.