query_selector_all
Execute querySelectorAll on a DOM node. Args: node_id: Target node ID to query within selector: CSS selector string Returns: Array of node IDs matching the selector
This record as markdown: /tools/benjaminr-chrome-devtools-mcp/query-selector-all.md
What query_selector_all does on Chrome Devtools
AI agents call query_selector_all to retrieve information from Chrome Devtools without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Why query_selector_all is rated Low
querySelectorAll is a standard read-only DOM API that queries and retrieves references to elements matching a CSS selector. It has no side effects, does not modify data, and does not execute code or trigger external operations. While it executes in a browser context via DevTools Protocol, the operation itself is purely informational retrieval.
From the tool's definition Tool executes querySelectorAll on a DOM node and returns matching node IDs. The description states it 'Execute[s] querySelectorAll' which is a read-only DOM query operation that retrieves element references without modifying state or triggering side effects.
Risk signalsBulk/mass operation — affects multiple targets
Attacks that exploit this kind of access
The rule that runs query_selector_all safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Chrome Devtools, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For query_selector_all, this is the rule to start with:
query_selector_all is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Chrome Devtools, apply this rule, and every query_selector_all call is checked against it from then on.
Questions about query_selector_all
Execute querySelectorAll on a DOM node. Args: node_id: Target node ID to query within selector: CSS selector string Returns: Array of node IDs matching the selector. It is categorised as a Read tool in the Chrome Devtools MCP Server, which means it retrieves data without modifying state.
Register the Chrome Devtools MCP server in PolicyLayer and add a rule for query_selector_all: 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 Chrome Devtools. Nothing to install.
query_selector_all 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_selector_all 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_selector_all. 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_selector_all is provided by the Chrome Devtools MCP server (benjaminr/chrome-devtools-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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