AI agents invoke set_emote_parameter to trigger actions in VRChat MCP OSC. 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 triggers an emote action on a VRChat avatar, which executes an external operation (an animation/emote) in the VRChat environment. It modifies avatar state by triggering a real-time action in a live virtual environment. While not destructive or financial, it executes an external operation with side effects in VRChat.
From the tool's definition Set VRCEmote on the current avatar
Documented attack patterns abuse exactly the kind of access set_emote_parameter gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and VRChat MCP OSC, and nothing reaches the server without passing your rules. This is the rule we recommend for set_emote_parameter:
{
"version": "1",
"default": "deny",
"tools": {
"set_emote_parameter": {
"limits": [
{
"counter": "set_emote_parameter_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}set_emote_parameter 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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Set VRCEmote on the current avatar. It is categorised as a Execute tool in the VRChat MCP OSC MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the VRChat MCP OSC MCP server in PolicyLayer and add a rule for set_emote_parameter: 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 VRChat MCP OSC. Nothing to install.
set_emote_parameter 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 set_emote_parameter 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 set_emote_parameter. 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.
set_emote_parameter is provided by the VRChat MCP OSC MCP server (krekun/vrchat-mcp-osc). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from VRChat MCP OSC, 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.
12 VRChat MCP OSC tools catalogued and risk-classified — across an index of 43,000+ MCP servers.