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Mehmoodqureshi

MCP Browser Extension

by Mehmoodqureshi
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auth_check

Detects sign-in walls by reading URL, title, password fields, and controls; returns authRequired, confidence, and signals to separate expired sessions from lost agents.

Instructions

Is the tab sitting on a sign-in wall? Reads the page (URL, title, password fields, sign-in controls) and returns { authRequired, confidence, signals }. Use it after a navigate, or whenever a step fails unexpectedly, to tell "the session expired" apart from "the agent got lost". Pass failOnAuthWall:true to get an [AUTH_REQUIRED] error instead of a verdict, so a harness can bucket the run as an auth failure.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
tabIdNoTab id (default: agent's tab)
frameIdNoFrame id from frames_list
allFramesNoAct on the first match in ANY frame (the element may be in an iframe)
failOnAuthWallNoError with [AUTH_REQUIRED] if this lands on a sign-in wall (expired session)

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changedv0.9.24
    • changedInput schema / properties / tabId / description
      Previous value: -"Tab id (default: active tab)"New value: +"Tab id (default: agent's tab)"
  2. Changed4 schema fields changedv0.9.5
    • changedInput schema / properties / allFrames / description
      Previous value: -"Search every frame of the tab and act on the first that matches - use when a selector should match but does not (the element is in an iframe)"New value: +"Act on the first match in ANY frame (the element may be in an iframe)"
    • changedInput schema / properties / failOnAuthWall / description
      Previous value: -"Fail with [AUTH_REQUIRED] when the page this call lands on is a high-confidence sign-in wall (session expired). Off by default unless the server runs with --fail-on-auth-wall; snapshot still reports the verdict as `authWall` either way."New value: +"Error with [AUTH_REQUIRED] if this lands on a sign-in wall (expired session)"
    • changedInput schema / properties / frameId / description
      Previous value: -"Act inside this frame (ids come from frames_list)"New value: +"Frame id from frames_list"
    • changedInput schema / properties / tabId / description
      Previous value: -"Target tab id (defaults to the active tab)"New value: +"Tab id (default: active tab)"
  3. Addedv0.9.3

TDQS

A4.5/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description carries the full burden, and it does disclose what is inspected, the returned payload keys, and the non-obvious side effect that failOnAuthWall:true converts the verdict into an [AUTH_REQUIRED] error rather than returning data. It does not cover latency, whether it navigates/waits, or false-positive behavior.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core question, then what it reads, then the return shape, then usage, then the flag. Every sentence adds information; nothing is restated from the schema or title.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

There is no output schema, and the description compensates by naming the return object's fields ({ authRequired, confidence, signals }). Combined with the usage triggers and the error-mode behavior, an agent has everything needed to call this correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3. The description adds real meaning for failOnAuthWall (error vs verdict, and the harness-bucketing use case) that the schema's one-line hint only gestures at, though tabId/frameId/allFrames are left entirely to the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource up front ('Is the tab sitting on a sign-in wall?') and immediately names the concrete signals it inspects (URL, title, password fields, sign-in controls) plus the verdict shape. An agent can distinguish this from generic readers like snapshot, get_html, or get_text without opening the schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives clear triggering contexts: 'after a navigate, or whenever a step fails unexpectedly', and frames the purpose as disambiguating 'session expired' from 'agent got lost'. It also explains the failOnAuthWall variant for harnesses. It stops short of naming a sibling tool or stating when-not to use it, so it is strong context rather than full alternative routing.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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