AI agents invoke stackchan_nod to trigger actions in Stackchan. 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.
Based on the server context, this tool likely triggers a nodding motion on the Stack-chan robot, which constitutes executing a physical action on an external device. The description is empty, lowering confidence, but the naming pattern alongside sibling tools (move, shake) strongly implies physical movement execution. Severity is medium as misuse could cause unintended robot movement but has limited blast radius.
From the tool's definition Tool name 'stackchan_nod' on a server that 'enables speech, listening, vision, movement, and facial expressions through MCP tool calls'; sibling tools include stackchan_move and stackchan_shake suggesting physical robot actuation.
Documented attack patterns abuse exactly the kind of access stackchan_nod gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Stackchan, and nothing reaches the server without passing your rules. This is the rule we recommend for stackchan_nod:
{
"version": "1",
"default": "deny",
"tools": {
"stackchan_nod": {
"limits": [
{
"counter": "stackchan_nod_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}stackchan_nod 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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stackchan_nod. It is categorised as a Execute tool in the Stackchan MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Stackchan MCP server in PolicyLayer and add a rule for stackchan_nod: 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 Stackchan. Nothing to install.
stackchan_nod 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 stackchan_nod 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 stackchan_nod. 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.
stackchan_nod is provided by the Stackchan MCP server (migratorywhale/stackchan-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Stackchan, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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12 Stackchan tools catalogued and risk-classified — across an index of 43,000+ MCP servers.