save_screenshot · Selenium MCP: Risk & Policy

WHAT IT DOES

What save_screenshot does on SeleniumMCP

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

WHY IT NEEDS A POLICY

Why save_screenshot needs a policy

This tool writes a file (PNG screenshot) to the server's local filesystem. It creates/overwrites a file, which is a Write operation. Severity is medium because an AI agent could write files to arbitrary server paths, but it does not execute code or delete data.

From the tool's definition Save a PNG screenshot to a server-local path and return the path

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

save_screenshot Rate-limited

save_screenshot 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": {
    "save_screenshot": {
      "limits": [
        {
          "counter": "save_screenshot_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 SeleniumMCP, so you can run agents against it safely.

FAQ

Questions about save_screenshot

What does the save_screenshot tool do? +

Save a PNG screenshot to a server-local path and return the path. It is categorised as a Write tool in the SeleniumMCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on save_screenshot? +

Register the Selenium MCP server in PolicyLayer and add a rule for save_screenshot: 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 SeleniumMCP. Nothing to install.

What risk level is save_screenshot? +

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

Can I rate-limit save_screenshot? +

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

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

save_screenshot is provided by the Selenium MCP server (lokii0911/seleniummcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.