@webability/mcp

by snayyar00

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TypeScript

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Scan a page for accessibility issues

scan_page

Read-onlyIdempotent

Instructions

Scan a web page for WCAG accessibility issues. Works on any URL — deployed sites, localhost, staging. Returns issues (violations the scanner stands behind; findings the engines cannot decide are settled by the AI judge — a violation with a fix, or a pass recorded in judged[] with its reason — and anything unsettled is dropped, never listed for review) and a summary. On React ≤18 / Vue dev builds each issue carries source ({file, line, column, component}) read from the live component tree. Every issue carries a structured fix.op (add-attribute | set-attribute | remove-attribute | add-element | remove-element | add-text-content | suggest) with fix.attribute / fix.value when known, and a fixability tier (mechanical = apply as given; contextual = op known, value needs judgment; visual = needs rendered output, propose only).

Input Schema

TableJSON Schema

Name	Required	Description
`url`	Yes	URL to scan (e.g. https://webability.io or http://localhost:3000)
`wcag`	No	Only these WCAG criteria. A prefix selects the whole guideline ("1.4") or principle ("2").
`level`	No	Highest WCAG conformance level to report. Default "AA" — Level AAA criteria are not reported. Pass "AAA" to include them (naming one AAA criterion in `wcag`, e.g. "3.2.5", also includes it).
`rules`	No	Only these rule ids (WebAbility type such as "missing_alt" or axe rule id such as "image-alt"). See get_rules.
`format`	No	"compact" prints one line per element with rule metadata once. "json" returns every field (html, fix values, source). Default: JSON when it fits inline (under ~24k chars), otherwise compact plus a JSON summary of every count.
`viewport`	No	Viewport size (default: desktop)
`minImpact`	No	Only findings at this severity or above (critical > serious > moderate > minor)
`sourceRoot`	No	Local project root (local installs only). Issues without a framework `source` pointer get `sourceCandidates[]` — files whose contents match the selector's id/class/attribute tokens.
`rootSelector`	No	CSS selector to limit scan scope (optional)

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv1.8.0Oct 7, 2026

addedInput schema / properties / level

Added value: +{
+  "description": "Highest WCAG conformance level to report. Default \"AA\" — Level AAA criteria are not reported. Pass \"AAA\" to include them (naming one AAA criterion in `wcag`, e.g. \"3.2.5\", also includes it).",
+  "enum": [
+    "A",
+    "AA",
+    "AAA"
+  ],
+  "type": "string"
+}

Changed6 schema fields changedv1.7.0Oct 5, 2026

addedInput schema / properties / format

Added value: +{
+  "description": "\"compact\" prints one line per element with rule metadata once. \"json\" returns every field (html, fix values, source). Default: JSON when it fits inline (under ~24k chars), otherwise compact plus a JSON summary of every count.",
+  "enum": [
+    "json",
+    "compact"
+  ],
+  "type": "string"
+}

addedInput schema / properties / minImpact

Added value: +{
+  "description": "Only findings at this severity or above (critical > serious > moderate > minor)",
+  "enum": [
+    "critical",
+    "serious",
+    "moderate",
+    "minor"
+  ],
+  "type": "string"
+}

addedInput schema / properties / rules

Added value: +{
+  "description": "Only these rule ids (WebAbility type such as \"missing_alt\" or axe rule id such as \"image-alt\"). See get_rules.",
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

addedInput schema / properties / sourceRoot

Added value: +{
+  "description": "Local project root (local installs only). Issues without a framework `source` pointer get `sourceCandidates[]` — files whose contents match the selector's id/class/attribute tokens.",
+  "type": "string"
+}

changedInput schema / properties / url / description

Previous value: -"URL to scan (e.g. https://example.com or http://localhost:3000)"New value: +"URL to scan (e.g. https://webability.io or http://localhost:3000)"

addedInput schema / properties / wcag

Added value: +{
+  "description": "Only these WCAG criteria. A prefix selects the whole guideline (\"1.4\") or principle (\"2\").",
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

First observedv1.3.1Jul 11, 2026

TDQS

A3.9/5.0

Behavior5/5

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

Annotations establish read-only/idempotent safety, and the description goes well beyond them: it explains that ambiguous findings are adjudicated by an AI judge, that unsettled findings are dropped and never surfaced for review, that `source` only appears on React ≤18 / Vue dev builds, and it defines the `fix.op` vocabulary and the mechanical/contextual/visual fixability tiers. That is exactly the behavioral context needed to decide whether to act on results or hand off to verify_fix/generate_ai_fix.

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

Conciseness4/5

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

Front-loaded with purpose, then spends its length on return-shape detail that genuinely matters because there is no output schema. The middle sentence is over-nested with em-dash parentheticals and could be split, costing it the top score.

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

Completeness4/5

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

With no output schema, the description carries the return-value burden and does it well (`issues`, `summary`, `judged[]`, `source`, `fix.op`, `fixability`). It omits runtime characteristics such as scan duration, rate limits, or auth requirements for the hosted service, which leaves a modest gap for a 9-parameter scanning tool.

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% and the schema already documents url, wcag, level, rules, format, viewport, minImpact, sourceRoot, and rootSelector in detail. The description adds no parameter-level meaning beyond that, so the baseline of 3 applies.

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

Purpose4/5

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

States a specific verb+resource ("Scan a web page for WCAG accessibility issues") and scopes the input surface ("Works on any URL — deployed sites, localhost, staging"). It does not name the siblings it competes with (flow_scan, scan_html, diff_scan, visual_audit), so an agent must infer the boundary rather than read it.

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 implies when the tool applies (any URL, including localhost and staging) but never states when NOT to use it or which sibling to pick instead for flows, raw HTML, visual audits, or diffs. Usage is inferable but not routed.

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

Scan a page for accessibility issues

Instructions

Input Schema

Schema Changelog

TDQS

Other Tools