screenshot_viewport · MCP Browser Screenshot Server MCP

WHAT IT DOES

What screenshot_viewport does on MCP Browser Screenshot Server

AI agents invoke screenshot_viewport to trigger actions in MCP Browser Screenshot Server. 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 screenshot_viewport needs a policy

Taking a viewport screenshot requires executing an automated browser session, which involves external operations (browser launch, navigation, rendering) whose effects depend on the provided arguments such as viewport dimensions and target URL. The server description explicitly mentions 'automated browser sessions' and 'JavaScript execution', elevating this beyond a simple read operation.

From the tool's definition 'Take a screenshot with specific viewport settings' — involves launching/controlling an automated browser session with configured viewport parameters

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

screenshot_viewport Rate-limited

screenshot_viewport 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": {
    "screenshot_viewport": {
      "limits": [
        {
          "counter": "screenshot_viewport_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 MCP Browser Screenshot Server, so you can run agents against it safely.

FAQ

Questions about screenshot_viewport

What does the screenshot_viewport tool do? +

Take a screenshot with specific viewport settings. It is categorised as a Execute tool in the MCP Browser Screenshot Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on screenshot_viewport? +

Register the MCP Browser Screenshot Server MCP server in PolicyLayer and add a rule for screenshot_viewport: 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 MCP Browser Screenshot Server. Nothing to install.

What risk level is screenshot_viewport? +

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

Can I rate-limit screenshot_viewport? +

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

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

screenshot_viewport is provided by the MCP Browser Screenshot Server MCP server (seabassgonzalez/mcp-browser-screenshot). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.