compress_image · FFmpeg MCP Tool MCP: Risk & Policy

WHAT IT DOES

What compress_image does on FFmpeg MCP Tool

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

WHY IT NEEDS A POLICY

Why compress_image needs a policy

Image compression is a reversible modification operation — the original file can be recovered or a new compressed version created without permanent data loss. This fits Write (creates or modifies data reversibly) rather than Destructive.

From the tool's definition Tool performs image compression ("compress_image"), which modifies file data. Description states "压缩单个图片文件" (compress a single image file). This creates a new or modified version of the image file.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

compress_image Rate-limited

compress_image 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": {
    "compress_image": {
      "limits": [
        {
          "counter": "compress_image_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 MCP Tool, so you can run agents against it safely.

FAQ

Questions about compress_image

What does the compress_image tool do? +

压缩单个图片文件. It is categorised as a Write tool in the FFmpeg MCP Tool MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on compress_image? +

Register the FFmpeg MCP Tool MCP server in PolicyLayer and add a rule for compress_image: 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 MCP Tool. Nothing to install.

What risk level is compress_image? +

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

Can I rate-limit compress_image? +

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

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

compress_image is provided by the FFmpeg MCP Tool MCP server (lbjwt/ffmpeg-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.