AI agents invoke rest to trigger actions in Reachy Mini MCP. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
This tool directly actuates a physical robot by controlling its rest state, which involves motor commands and physical movement. It is an external operation whose effects depend on arguments and act on physical hardware. While 'rest' could mean putting motors into a low-power/safe state, it still triggers a physical hardware operation.
From the tool's definition 'Control robot rest state' — triggers a physical state change on a real robot (Reachy Mini), affecting its motors and posture.
Documented attack patterns abuse exactly the kind of access rest gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Reachy Mini MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for rest:
{
"version": "1",
"default": "deny",
"tools": {
"rest": {
"limits": [
{
"counter": "rest_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}rest stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
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Control robot rest state. It is categorised as a Execute tool in the Reachy Mini MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Reachy Mini MCP server in PolicyLayer and add a rule for rest: 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 Reachy Mini MCP. Nothing to install.
rest is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the rest 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 rest. 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.
rest is provided by the Reachy Mini MCP server (jackccrawford/reachy-mini-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Reachy Mini MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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7 Reachy Mini MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.