go_to_frame · Vmd MCP: Risk & Policy

WHAT IT DOES

What go_to_frame does on Vmd

AI agents invoke go_to_frame to trigger actions in Vmd. 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 go_to_frame needs a policy

This tool changes the current frame of a trajectory in the running VMD application. It is not a passive read (it modifies application state), not a write to persistent data, and not destructive or financial. It executes an operation that alters the VMD session state, similar to a UI action/trigger, placing it in the Execute category.

From the tool's definition 'Jump the trajectory of a molecule to a specific frame number' — triggers a state change in the VMD application, navigating playback position

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

go_to_frame Rate-limited

go_to_frame 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": {
    "go_to_frame": {
      "limits": [
        {
          "counter": "go_to_frame_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 Vmd, so you can run agents against it safely.

FAQ

Questions about go_to_frame

What does the go_to_frame tool do? +

Jump the trajectory of a molecule to a specific frame number. It is categorised as a Execute tool in the Vmd MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on go_to_frame? +

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

What risk level is go_to_frame? +

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

Can I rate-limit go_to_frame? +

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

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

go_to_frame is provided by the Vmd MCP server (omararias-gaguancela/vmd-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.