Take a screenshot of the current browser page. Uses Chrome DevTools Protocol for reliable capture (requires Chrome launched with --remote-debugging-port=9222). Falls back to bookmarklet capture if CDP unavailable.
AI agents call trigger_screenshot to retrieve information from Mcp Browser Lens without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool captures a screenshot of the current page, which is a read-only operation with no side effects. It retrieves visual data from the browser without modifying any state. The blast radius is low as it can only read what's currently displayed in the browser.
From the tool's definition Take a screenshot of the current browser page... Falls back to bookmarklet capture if CDP unavailable.
Attacks that exploit this kind of access
Take a screenshot of the current browser page. Uses Chrome DevTools Protocol for reliable capture (requires Chrome launched with --remote-debugging-port=9222). Falls back to bookmarklet capture if CDP unavailable. It is categorised as a Read tool in the Mcp Browser Lens MCP Server, which means it retrieves data without modifying state.
Register the Mcp Browser Lens MCP server in PolicyLayer and add a rule for trigger_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 Mcp Browser Lens. Nothing to install.
trigger_screenshot is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the trigger_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.
Set action: deny in the PolicyLayer policy for trigger_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.
trigger_screenshot is provided by the Mcp Browser Lens MCP server (nano-step/mcp-browser-lens). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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