take_screenshot

Capture device screen as JPEG. EXPENSIVE: consumes large image tokens. Prefer text-based tools first: query_selector/assert_text for native UI, webview_evaluate_script for WebView DOM. Use screenshot only when visual layout check is needed or text tools cannot verify the state. After one screensh...

Server React Native @ohah/react-native-mcp-server
Category Read
Risk class Low
Parameters 00 required

What take_screenshot does on React Native

AI agents call take_screenshot to retrieve information from React Native without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

Why take_screenshot needs a policy

Taking a screenshot is a non-destructive read operation that retrieves visual information about the current UI state without side effects. While it consumes tokens/resources, it does not create, modify, delete, execute code, or commit financial transactions.

From the tool's definition Tool captures and retrieves device screen as JPEG without modifying app state, data, or triggering external operations.

Questions about take_screenshot

What does the take_screenshot tool do? +

Capture device screen as JPEG. EXPENSIVE: consumes large image tokens. Prefer text-based tools first: query_selector/assert_text for native UI, webview_evaluate_script for WebView DOM. Use screenshot only when visual layout check is needed or text tools cannot verify the state. After one screenshot, switch back to text-based tools. It is categorised as a Read tool in the React Native MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on take_screenshot? +

Register the React Native MCP server in PolicyLayer and add a rule for take_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 React Native. Nothing to install.

What risk level is take_screenshot? +

take_screenshot is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit take_screenshot? +

Yes. Add a rate_limit block to the take_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 take_screenshot completely? +

Set action: deny in the PolicyLayer policy for take_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 take_screenshot? +

take_screenshot is provided by the React Native MCP server (@ohah/react-native-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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