AI agents call get_ui_tree to retrieve information from Rn Debug without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves debugging information about the current UI state without creating, modifying, deleting, executing code, or causing side effects. It is a read-only diagnostic operation typical of mobile app debugging tools.
From the tool's definition Tool description explicitly states 'Read the current accessibility hierarchy' - the verb 'Read' and the operation of retrieving UI structure from existing debugging frameworks (Android UIAutomator, iOS WDA) without modification.
Attacks that exploit this kind of access
Read the current accessibility hierarchy from Android UIAutomator or iOS WDA. It is categorised as a Read tool in the Rn Debug MCP Server, which means it retrieves data without modifying state.
Register the Rn Debug MCP server in PolicyLayer and add a rule for get_ui_tree: 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 Rn Debug. Nothing to install.
get_ui_tree 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 get_ui_tree 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 get_ui_tree. 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.
get_ui_tree is provided by the Rn Debug MCP server (rn-debug-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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