start_relaxation · Fairchem MCP: Risk & Policy

WHAT IT DOES

What start_relaxation does on Fairchem

AI agents invoke start_relaxation to trigger actions in Fairchem. 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.

WHY IT NEEDS A POLICY

Why start_relaxation needs a policy

This tool initiates a molecular dynamics relaxation simulation, which is a computational operation with effects that depend on input arguments (structure, force field, convergence criteria). While the description is empty, context from the server design and sibling tools makes clear this executes external simulations.

From the tool's definition Tool named 'start_relaxation' on a computational chemistry server that runs FAIRChem and ASE simulations. Sibling tools include 'attach_emt', 'attach_lammps', 'execute', and 'get_trajectory', indicating this server orchestrates computational workflows.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

start_relaxation Rate-limited

start_relaxation 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "start_relaxation": {
      "limits": [
        {
          "counter": "start_relaxation_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-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 start_relaxation

What does the start_relaxation tool do? +

start_relaxation. It is categorised as a Execute tool in the Fairchem MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on start_relaxation? +

Register the Fairchem MCP server in PolicyLayer and add a rule for start_relaxation: 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 start_relaxation? +

start_relaxation is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit start_relaxation? +

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

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

start_relaxation 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.