get_computed_styles

THE RISK

Low Risk

Why get_computed_styles needs a policy

The tool retrieves and queries CSS style data from a browser element without modifying, executing code, deleting data, or moving money. It is purely informational for debugging purposes. The blast radius of misuse is minimal—an agent could only gather UI styling information, which poses no security or operational risk.

From the tool's definition Tool name 'get_computed_styles' and description 'Returns the computed CSS styles for an element' indicate a read-only retrieval operation with no side effects. This is a query for UI debugging information.

Documented attack patterns abuse exactly the kind of access get_computed_styles gives an agent:

POLICY

How to control get_computed_styles

PolicyLayer is an MCP gateway — it sits between your AI agents and Chrome MCP Docker, and nothing reaches the server without passing your rules. This is the rule we recommend for get_computed_styles:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "get_computed_styles": {}
  }
}

get_computed_styles is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register Chrome MCP Docker — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

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EXPLORE

Related tools and policies

More Chrome MCP Docker tools

Execute navigate Navigates to a URL and waits for network idle. Execute wait_for_selector Waits for an element to appear in the DOM. Execute mobile_mode Toggles mobile viewport (iPhone X dimensions). Execute click Clicks an element identified by CSS selector. Execute scroll Scrolls the page. Use x,y coordinates OR selector to scroll into view. Write type Types text into an input field. Read get_console_logs Returns captured console logs (errors, warnings, info). Useful for debugging JS issues. Read get_network_errors Returns a list of failed network requests.

All 10 Chrome MCP Docker tools →

Read tools on other servers

M-Team MCP Server get_torrent_detail YouTube MCP Server search_channel Android Forensics ADB MCP Server parse_browser_history 0xarchive web3_challenge

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about get_computed_styles

What does the get_computed_styles tool do? +

Returns the computed CSS styles for an element (essential for UI debugging). It is categorised as a Read tool in the Chrome MCP Docker MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on get_computed_styles? +

Register the Chrome MCP Docker MCP server in PolicyLayer and add a rule for get_computed_styles: 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 MCP Docker. Nothing to install.

What risk level is get_computed_styles? +

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

Can I rate-limit get_computed_styles? +

Yes. Add a rate_limit block to the get_computed_styles 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 get_computed_styles completely? +

Set action: deny in the PolicyLayer policy for get_computed_styles. 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 get_computed_styles? +

get_computed_styles is provided by the Chrome MCP Docker MCP server (null-runner/chrome-mcp-docker). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Chrome MCP Docker tool call.

Start from Chrome MCP Docker, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →