Query a DOM element by CSS selector. Returns bounding rect, attributes, computed styles, inner text, and child count. Use this to debug layout, positioning, and visibility issues. Requires a connected browser session. If you get BROWSER_NOT_CONNECTED, call check_session first and wait for "connec...
Risk signalsHandles credentials or secrets (secret)
Part of the Sncro server.
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AI agents call query_element to retrieve information from Sncro without modifying any data. This is common in research, monitoring, and reporting workflows where the agent needs context before taking action. Because read operations don't change state, they are generally safe to allow without restrictions -- but you may still want rate limits to control API costs.
Even though query_element only reads data, uncontrolled read access can leak sensitive information or rack up API costs. An agent caught in a retry loop could make thousands of calls per minute. A rate limit gives you a safety net without blocking legitimate use.
Read-only tools are safe to allow by default. No rate limit needed unless you want to control costs.
{
"version": "1",
"default": "deny",
"tools": {
"query_element": {}
}
}See the full Sncro policy for all 12 tools.
These attack patterns abuse exactly the kind of access query_element gives an agent. Each links to the full case and the policy that stops it:
Other read tools across the catalogue. The same approach applies to each: allow, with a rate cap to control cost.
Query a DOM element by CSS selector. Returns bounding rect, attributes, computed styles, inner text, and child count. Use this to debug layout, positioning, and visibility issues. Requires a connected browser session. If you get BROWSER_NOT_CONNECTED, call check_session first and wait for "connected" status. If you get BROWSER_TIMEOUT, the page may be navigating — wait a moment and retry. Args: key: The sncro session key secret: The session secret from create_session selector: CSS selector (e.g. "#photo-wrap", ".toolbar > button:first-child") styles: Optional list of CSS properties to read (e.g. ["transform", "width", "display"]). It is categorised as a Read tool in the Sncro MCP Server, which means it retrieves data without modifying state.
Register the Sncro MCP server in PolicyLayer and add a rule for query_element: 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 Sncro. Nothing to install.
query_element 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_element 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_element. 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_element is provided by the Sncro MCP server (https://relay.sncro.net/tools/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 12 Sncro tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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