browser_auth_from_api_login · MCP: Risk & Policy

WHAT IT DOES

What browser_auth_from_api_login does on Mcp

AI agents invoke browser_auth_from_api_login to trigger actions in Mcp. 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_auth_from_api_login needs a policy

This tool performs an API login and writes authentication tokens into the browser's localStorage, which is an external operation with significant security implications. It spans Write (persisting tokens) and Execute (triggering an API login and browser state manipulation). The most severe applicable category is Execute due to the side-effecting browser/API interaction.

From the tool's definition Authenticate frontend state by API login and persist tokens into localStorage for the current browser origin

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

browser_auth_from_api_login Rate-limited

browser_auth_from_api_login 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_auth_from_api_login": {
      "limits": [
        {
          "counter": "browser_auth_from_api_login_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 Mcp, so you can run agents against it safely.

FAQ

Questions about browser_auth_from_api_login

What does the browser_auth_from_api_login tool do? +

Authenticate frontend state by API login and persist tokens into localStorage for the current browser origin. It is categorised as a Execute tool in the Mcp 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_auth_from_api_login? +

Register the MCP server in PolicyLayer and add a rule for browser_auth_from_api_login: 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 Mcp. Nothing to install.

What risk level is browser_auth_from_api_login? +

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

Can I rate-limit browser_auth_from_api_login? +

Yes. Add a rate_limit block to the browser_auth_from_api_login 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_auth_from_api_login completely? +

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

browser_auth_from_api_login is provided by the MCP server (victormyschik/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.