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Measure every page for sideways scroll

check_responsive

Read-only

Tests pages at multiple viewport widths in a real browser, flags horizontal overflow, and names the elements that cross the viewport edge.

Instructions

Loads each page in a real headless Chromium at a set of widths and asserts that document.documentElement.scrollWidth does not exceed window.innerWidth. Reports the actual numbers at every width, pass or fail, and names the specific elements whose edge crosses the line.

Requires Playwright, which is NOT installed with this kit. If it is missing this tool returns status "skipped" with the one command that installs it. It never reports a pass it did not measure.

Input Schema

TableJSON Schema

Name	Required	Description
`pages`	No	Specific .html files to test, relative to the site folder. Default: every .html file found.
`height`	No	Viewport height. Default 900.
`ignore`	No	Folder or file names to skip. Defaults cover node_modules, .git, dist, build and friends.
`widths`	No	Viewport widths in CSS pixels. Default: 320, 390, 768, 1024, 1280, 1440
`directory`	Yes	Full path to the site folder, for example /Users/brian/Sites/chess-lessons.
`timeout_ms`	No	Per-page load timeout. Default 20000.

Output Schema

TableJSON Schema

Name	Required	Description
`fix`	No
`why`	No
`tool`	Yes	Which tool produced this.
`status`	Yes	pass = checked and clean. fail = checked and found problems. skipped = nothing was measured. error = the tool could not run.
`widths`	No
`problem`	No
`headline`	Yes	One sentence verdict, safe to show a non-technical user.
`directory`	No
`error_code`	No	Set only when status is "error".
`page_errors`	No
`browser_from`	No
`measurements`	No
`pages_tested`	No
`overflow_count`	No
`install_command`	No
`browser_available`	No
`measurements_taken`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv2.0.0Sep 17, 2026

TDQS

A4.3/5.0

Behavior5/5

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

Annotations only say readOnlyHint and openWorldHint; the description adds substantial behavioral context: real Chromium, exact assertion, per-width reporting, named offending elements, the skipped status when Playwright is missing, and a guarantee that it never reports an unmeasured pass. This far exceeds the annotation baseline without contradicting it.

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?

The description is tight and dense: one sentence states the core behavior and reporting, and a short dependency note covers setup and failure mode. Every sentence earns its place, with the most important assertion front-loaded.

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?

Given the rich input schema, output schema, and safety annotations, the description covers the remaining decision-relevant context: exact criterion, output behavior, dependency requirement, and skip semantics. Nothing essential is missing for an agent to select and invoke this tool correctly.

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?

Schema description coverage is 100%, with defaults and bounds documented for all six parameters, so the description does not need to repeat parameter details. The description contributes only a generic reference to 'a set of widths,' which does not add semantic value beyond 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?

The description states a concrete, specific behavior: load each page in headless Chromium and assert that scrollWidth does not exceed innerWidth. This precise scope clearly distinguishes it from the sibling check_* tools, all of which target different concerns.

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

Usage Guidelines3/5

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

The description makes the tool's context clear from its operation, but it never explicitly says when to prefer this tool over alternatives or when not to use it. No sibling comparison or exclusion is given, so usage guidance is mostly implied by the title and behavior rather than stated.

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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