Search the accessibility tree by ARIA role and/or accessible name.
AI agents call query_accessibility_tree to retrieve information from MCP Accessibility Bridge without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries and retrieves information from the browser's accessibility tree without creating, modifying, deleting, or executing operations. It is purely informational—reading element roles and states from the DOM for testing and debugging purposes. There are no side effects or external operations triggered. Low severity because misuse would only expose UI structure information already visible to the user.
From the tool's definition Tool name is 'query_accessibility_tree' and description states it 'Search[es] the accessibility tree by ARIA role and/or accessible name.' The verb 'search' and the absence of any modification language indicate data retrieval only.
Documented attack patterns abuse exactly the kind of access query_accessibility_tree gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MCP Accessibility Bridge, and nothing reaches the server without passing your rules. This is the rule we recommend for query_accessibility_tree:
{
"version": "1",
"default": "deny",
"tools": {
"query_accessibility_tree": {}
}
}query_accessibility_tree is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Search the accessibility tree by ARIA role and/or accessible name. It is categorised as a Read tool in the MCP Accessibility Bridge MCP Server, which means it retrieves data without modifying state.
Register the MCP Accessibility Bridge MCP server in PolicyLayer and add a rule for query_accessibility_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 MCP Accessibility Bridge. Nothing to install.
query_accessibility_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 query_accessibility_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 query_accessibility_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.
query_accessibility_tree is provided by the MCP Accessibility Bridge MCP server (yashpreetbathla/mcp-accessibility-bridge). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from MCP Accessibility Bridge, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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8 MCP Accessibility Bridge tools catalogued and risk-classified — across an index of 43,000+ MCP servers.