browser_select · Claude Flow MCP: Risk & Policy

WHAT IT DOES

What browser_select does on Claude Flow

AI agents invoke browser_select to trigger actions in Claude Flow. 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.

WHY IT NEEDS A POLICY

Why browser_select needs a policy

This tool performs real browser automation actions (selecting dropdown options, navigating login flows, interacting with live DOM), which constitutes executing external operations with side effects. It can interact with authenticated sessions via cookie reuse, potentially triggering state changes on web applications.

From the tool's definition Select an option from a dropdown... real browser automation — JS-heavy SPA scraping, login flows with cookie reuse, replay against DOM-drifted versions

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

browser_select Rate-limited

browser_select 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "browser_select": {
      "limits": [
        {
          "counter": "browser_select_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Claude Flow, so you can run agents against it safely.

FAQ

Questions about browser_select

What does the browser_select tool do? +

Select an option from a dropdown Use when native WebFetch is wrong because you need real browser automation — JS-heavy SPA scraping, login flows with cookie reuse, replay against DOM-drifted versions, AIDefence PII gating before content reaches Claude. For static HTML pages, native WebFetch is faster and free. It is categorised as a Execute tool in the Claude Flow MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on browser_select? +

Register the Claude Flow MCP server in PolicyLayer and add a rule for browser_select: 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 Claude Flow. Nothing to install.

What risk level is browser_select? +

browser_select is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit browser_select? +

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

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

browser_select is provided by the Claude Flow MCP server (claude-flow). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.