set_thumbnail · YouTube MCP Server MCP: Risk & Policy

WHAT IT DOES

What set_thumbnail does on YouTube MCP Server

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

WHY IT NEEDS A POLICY

Why set_thumbnail needs a policy

This tool creates or modifies video metadata (the thumbnail image) reversibly—the thumbnail can be changed again or reverted. It does not delete data irreversibly, execute arbitrary code, or move money, placing it in the Write category. Severity is medium because a compromised agent could deface videos by setting inappropriate thumbnails, but the impact is limited to visual presentation and is easily reversible.

From the tool's definition The tool name 'set_thumbnail' and description 'Establecer una miniatura personalizada para un video' (Set a custom thumbnail for a video) indicate this modifies video metadata by uploading/setting a thumbnail image, which is a reversible modification to video…

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_thumbnail Rate-limited

set_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": {
    "set_thumbnail": {
      "limits": [
        {
          "counter": "set_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 YouTube MCP Server, so you can run agents against it safely.

FAQ

Questions about set_thumbnail

What does the set_thumbnail tool do? +

Establecer una miniatura personalizada para un video. It is categorised as a Write tool in the YouTube MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on set_thumbnail? +

Register the YouTube MCP Server MCP server in PolicyLayer and add a rule for set_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 YouTube MCP Server. Nothing to install.

What risk level is set_thumbnail? +

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

Can I rate-limit set_thumbnail? +

Yes. Add a rate_limit block to the set_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 set_thumbnail completely? +

Set action: deny in the PolicyLayer policy for set_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 set_thumbnail? +

set_thumbnail is provided by the YouTube MCP Server MCP server (nocodeboy/youtube-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.