Assert CSS property value using computed styles
AI agents invoke playwright_assert_css_property to trigger actions in RunAutomation MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
This tool runs a browser action (evaluating/asserting CSS computed styles) within a Playwright session. It doesn't just read data passively; it performs an active assertion operation in the browser context. The blast radius is low since it's a read-like assertion with no side effects beyond the browser session state.
From the tool's definition 'Assert CSS property value using computed styles' — executes a browser-side assertion by querying computed styles in an active browser session
Documented attack patterns abuse exactly the kind of access playwright_assert_css_property gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and RunAutomation MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for playwright_assert_css_property:
{
"version": "1",
"default": "deny",
"tools": {
"playwright_assert_css_property": {
"limits": [
{
"counter": "playwright_assert_css_property_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}playwright_assert_css_property stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
Free to start. No card required.
Assert CSS property value using computed styles. It is categorised as a Execute tool in the RunAutomation MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the RunAutomation MCP Server MCP server in PolicyLayer and add a rule for playwright_assert_css_property: 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 RunAutomation MCP Server. Nothing to install.
playwright_assert_css_property is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the playwright_assert_css_property 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 playwright_assert_css_property. 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.
playwright_assert_css_property is provided by the RunAutomation MCP Server MCP server (tayyabakmal1/runautomation-mcpserver). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from RunAutomation MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
91 RunAutomation MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.