attach_emt · Fairchem MCP: Risk & Policy

WHAT IT DOES

What attach_emt does on Fairchem

AI agents use attach_emt to create or update resources in Fairchem — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Fairchem environment.

WHY IT NEEDS A POLICY

Why attach_emt needs a policy

This tool attaches/assigns an EMT calculator to a simulation object, modifying the state of the running simulation environment. It is not purely reading data, nor does it execute a simulation run or destroy data — it configures/writes a calculator attachment.

From the tool's definition Attach a fast EMT calculator (no GPU/model needed)

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

attach_emt Rate-limited

attach_emt 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "attach_emt": {
      "limits": [
        {
          "counter": "attach_emt_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Fairchem, so you can run agents against it safely.

FAQ

Questions about attach_emt

What does the attach_emt tool do? +

Attach a fast EMT calculator (no GPU/model needed). Useful for quick tests. It is categorised as a Write tool in the Fairchem MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on attach_emt? +

Register the Fairchem MCP server in PolicyLayer and add a rule for attach_emt: 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 Fairchem. Nothing to install.

What risk level is attach_emt? +

attach_emt is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit attach_emt? +

Yes. Add a rate_limit block to the attach_emt 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 attach_emt completely? +

Set action: deny in the PolicyLayer policy for attach_emt. 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 attach_emt? +

attach_emt is provided by the Fairchem MCP server (jkitchin/fairchem-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.