Wait until JavaScript condition returns a truthy value. Args: condition_js: JavaScript expression or script. The return value is tested for truthiness. timeout: Maximum seconds to wait. interval: Seconds between checks. switch_tab_id: Optional tab ID to make active before waiting.
AI agents invoke browser_wait to trigger actions in Cdp Bridge. 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 allows execution of arbitrary JavaScript in an active browser tab, which can read sensitive page state, trigger side effects (API calls, form submissions), exfiltrate data, or interact with the page in unintended ways. While primarily designed for synchronization, the ability to execute arbitrary JS code with side effects makes this Execute-category.
From the tool's definition Tool executes arbitrary JavaScript expressions ('JavaScript expression or script') in a browser context and polls results until a condition is met. The 'condition_js' parameter accepts user-supplied code that runs in the page context.
Documented attack patterns abuse exactly the kind of access browser_wait gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Cdp Bridge, and nothing reaches the server without passing your rules. This is the rule we recommend for browser_wait:
{
"version": "1",
"default": "deny",
"tools": {
"browser_wait": {
"limits": [
{
"counter": "browser_wait_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}browser_wait 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.
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Wait until JavaScript condition returns a truthy value. Args: condition_js: JavaScript expression or script. The return value is tested for truthiness. timeout: Maximum seconds to wait. interval: Seconds between checks. switch_tab_id: Optional tab ID to make active before waiting. It is categorised as a Execute tool in the Cdp Bridge MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Cdp Bridge MCP server in PolicyLayer and add a rule for browser_wait: 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 Cdp Bridge. Nothing to install.
browser_wait 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 browser_wait 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 browser_wait. 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.
browser_wait is provided by the Cdp Bridge MCP server (unagi-cq/cdp-bridge-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 9 Cdp Bridge tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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9 Cdp Bridge tools catalogued and risk-classified — across an index of 42,500+ MCP servers.