AI agents use set_gravity to create or update resources in Threlte — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Threlte environment.
This tool modifies a global scene property (gravity vector) in the Three.js/Threlte scene. It is reversible since gravity can be changed again, making it a Write operation. Misuse could disrupt all physics simulations in the scene, giving it medium severity.
From the tool's definition Set global gravity vector
Documented attack patterns abuse exactly the kind of access set_gravity gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Threlte, and nothing reaches the server without passing your rules. This is the rule we recommend for set_gravity:
{
"version": "1",
"default": "deny",
"tools": {
"set_gravity": {
"limits": [
{
"counter": "set_gravity_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}set_gravity 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.
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Set global gravity vector. It is categorised as a Write tool in the Threlte MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Threlte MCP server in PolicyLayer and add a rule for set_gravity: 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 Threlte. Nothing to install.
set_gravity 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 set_gravity 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_gravity. 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_gravity is provided by the Threlte MCP server (serifeusstudio/threlte-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Threlte, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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30 Threlte tools catalogued and risk-classified — across an index of 43,000+ MCP servers.