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Mehmoodqureshi

chrome-mcp

by Mehmoodqureshi
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snapshot

Capture an accessibility tree of interactive elements with stable refs instead of guessing CSS selectors. Diff mode returns only changed elements from the last capture to cut cost in click/read loops.

Instructions

Accessibility snapshot: interactive elements with refs to target by ref (more reliable than guessing CSS selectors). Pass diff:true to get only what changed since the last snapshot of this tab - far cheaper in a click/read loop. Password fields appear as secret:true with no value.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
maxNo
diffNoReturn added/removed/changed elements since the previous snapshot of this tab instead of the whole tree
tabIdNoTab id (default: active 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)
interactiveOnlyNo

Schema Changelog

Changes observed during successful MCP inspections.

  1. 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)"
  2. Changed1 schema field changedv0.9.3
    • addedInput schema / properties / failOnAuthWall
      Added value: +{
+  "description": "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.",
+  "type": "boolean"
+}
  3. Changed3 schema fields changedv0.7.0
    • addedInput schema / properties / allFrames
      Added value: +{
+  "description": "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)",
+  "type": "boolean"
+}
    • addedInput schema / properties / diff
      Added value: +{
+  "description": "Return added/removed/changed elements since the previous snapshot of this tab instead of the whole tree",
+  "type": "boolean"
+}
    • addedInput schema / properties / frameId
      Added value: +{
+  "description": "Act inside this frame (ids come from frames_list)",
+  "type": "number"
+}
  4. First observedv0.6.2

TDQS

A4.1/5.0
Behavior4/5

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

With no annotations provided, the description carries the behavioral disclosure burden. It adds valuable details: refs are more reliable than CSS selectors, diff mode is cheaper, and password fields appear as secret:true with no value. It does not mention side effects or failure modes, but as a snapshot operation those are less critical.

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?

Three concise, front-loaded sentences cover purpose, ref targeting, diff use case, and password redaction. Every sentence adds a distinct piece of information with no redundancy or filler.

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

Completeness3/5

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

The core usage and security behavior are explained, but with no output schema and no annotations, the description leaves gaps around the full return shape and the undocumented `max` and `interactiveOnly` parameters. It is adequate for basic invocation but not fully complete for all 7 parameters.

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

Parameters3/5

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

The description adds useful meaning to the diff parameter by explaining its cost benefit, but it does not illuminate the `max` or `interactiveOnly` parameters, which lack schema descriptions. With 71% schema coverage and some added value, this sits at the baseline rather than above it.

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?

The description clearly identifies the tool as an accessibility snapshot returning interactive elements with stable `ref` identifiers, and distinguishes it from other inspection tools by emphasizing refs over CSS selectors. This gives an agent a precise sense of what the tool produces and why it is valuable.

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?

It provides clear context for when to use the tool (to get stable refs for interactive elements, especially in click/read loops) and when to use diff mode (to reduce cost). It stops short of explicitly naming sibling alternatives or stating when not to use snapshot, so it lacks the full when-not-to-use guidance of a 5.

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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