thumbnail · Ffmpeg MCP: Risk & Policy

WHAT IT DOES

What thumbnail does on Ffmpeg

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

WHY IT NEEDS A POLICY

Why thumbnail needs a policy

The thumbnail tool creates new image files derived from video input at specified times. This is a reversible write operation—the generated thumbnails can be deleted without affecting source videos. It has no destructive capability (doesn't delete originals), no execution of arbitrary code (performs deterministic media extraction), and no financial impact.

From the tool's definition Tool 'generates' and creates thumbnail 'image(s)' from video input, producing new files as output.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

thumbnail Rate-limited

thumbnail 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": {
    "thumbnail": {
      "limits": [
        {
          "counter": "thumbnail_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 Ffmpeg, so you can run agents against it safely.

FAQ

Questions about thumbnail

What does the thumbnail tool do? +

Generate thumbnail image(s) from video at a specific time or evenly spaced throughout. It is categorised as a Write tool in the Ffmpeg MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on thumbnail? +

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

What risk level is thumbnail? +

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

Can I rate-limit thumbnail? +

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

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

thumbnail is provided by the Ffmpeg MCP server (yuan66-hub/ffmpeg-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.