Accessibility Scanner MCP Server

MCP Accessibility Scanner 🔍

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A powerful Model Context Protocol (MCP) server that provides automated web accessibility scanning and browser automation using Playwright and Axe-core. This server enables LLMs to perform WCAG compliance checks, interact with web pages, manage persistent browser sessions, and generate detailed accessibility reports with visual annotations.

Features

Accessibility Scanning

✅ Full WCAG 2.0/2.1/2.2 compliance checking (A, AA, AAA levels)
📄 Detailed JSON reports with remediation guidance
🎯 Support for specific violation categories (color contrast, ARIA, forms, keyboard navigation, etc.)

Browser Automation

🖱️ Click, hover, and drag elements using accessibility snapshots
⌨️ Type text and handle keyboard inputs
🔍 Capture page snapshots to discover all interactive elements
📸 Take screenshots and save PDFs
🎯 Support for both element-based and coordinate-based interactions

Advanced Features

📑 Tab management for multi-page workflows
🌐 Monitor console messages and network requests
⏱️ Wait for dynamic content to load
📁 Handle file uploads and browser dialogs
🔄 Navigate through browser history

Installation

You can install the package using any of these methods:

Using npm:

npm install -g mcp-accessibility-scanner

Installation with Docker

A pre-built image is available on Docker Hub. The image includes Chromium and is pre-configured for containerized use — no extra flags needed.

Pull from Docker Hub:

docker pull justasmonkev/mcp-accessibility-scanner

Claude Code

 claude mcp add mcp-accessibility-scanner -s user -- docker run -i --rm justasmonkev/mcp-accessibility-scanner

To persist screenshots and reports on your host, add a volume mount:

claude mcp add mcp-accessibility-scanner -s user \
  -- docker run -i --rm -v /tmp/mcp-output:/app/output justasmonkev/mcp-accessibility-scanner

Without the -v mount, output files only exist inside the container and are lost when it exits.

Docker Compose

docker compose up -d

The Compose configuration publishes the unauthenticated MCP HTTP transport on 127.0.0.1:8931 only. Do not expose this port to untrusted networks.

Build from source

docker build -t mcp-accessibility-scanner .

Docker smoke test

npm run test:docker

Installation in VS Code

Install the Accessibility Scanner in VS Code using the VS Code CLI:

For VS Code:

code --add-mcp '{"name":"accessibility-scanner","command":"npx","args":["mcp-accessibility-scanner"]}'

For VS Code Insiders:

code-insiders --add-mcp '{"name":"accessibility-scanner","command":"npx","args":["mcp-accessibility-scanner"]}'

CLI Modes

The scanner can run in two modes depending on how you use it.

MCP server (default, no subcommand)

When launched without a subcommand, the process starts an MCP server that communicates over stdio. This is the mode used by MCP clients such as Claude Desktop, VS Code, and Claude Code -- you should never need to run it by hand.

npx mcp-accessibility-scanner            # starts the MCP server (stdio)

All of the MCP client configuration examples in this README already use this default mode.

Interactive REPL (interactive subcommand)

For manual terminal use, the interactive subcommand starts a readline REPL where you can call any tool directly:

$ npx mcp-accessibility-scanner interactive
Interactive mode. Type "<tool-name> <json>" to call a tool. Ctrl+D to exit.
> browser_navigate {"url": "https://example.com"}
> scan_page {"violationsTag": ["wcag21aa"]}
> audit_keyboard {"maxTabs": 30}
> audit_screen_reader {}

Each line is <tool-name> <json-arguments>. Omit the JSON to pass {}. Global browser connection flags still apply here, for example npx mcp-accessibility-scanner --headless interactive. Use --mobile or PLAYWRIGHT_MCP_MOBILE=1 to emulate a generic mobile device (Pixel 10 for Chromium, iPhone 17 for WebKit). It cannot be combined with --device, CDP attach/launch modes, remote browser endpoints, or --extension.

Browser extension mode

Use --extension to connect through the current Playwright Extension, which must support extension protocol v2.

npx mcp-accessibility-scanner --extension

Set PLAYWRIGHT_MCP_EXTENSION_TOKEN to the token shown by the extension to bypass the connection approval dialog. When --user-data-dir contains multiple Chrome profiles, the profile with the extension installed is selected automatically, preferring Chrome's last-used profile.

Discovering available tools (list-tools subcommand)

To print every tool name and its description:

npx mcp-accessibility-scanner list-tools

Note: Tool names like browser_navigate and scan_page are MCP tool identifiers (and REPL commands in interactive mode). They are not shell subcommands -- you cannot run npx mcp-accessibility-scanner browser_navigate.

Configuration

Here's the Claude Desktop configuration:

{
  "mcpServers": {
    "accessibility-scanner": {
      "command": "npx",
      "args": ["-y", "mcp-accessibility-scanner"]
    }
  }
}

Advanced Configuration

You can pass a configuration file to customize Playwright behavior:

{
  "mcpServers": {
    "accessibility-scanner": {
      "command": "npx",
      "args": ["-y", "mcp-accessibility-scanner", "--config", "/path/to/config.json"]
    }
  }
}

Configuration Options

Create a config.json file with the following options:

{
  "browser": {
    "browserName": "chromium",
    "launchOptions": {
      "headless": true,
      "channel": "chrome"
    },
    "cdpLaunch": {
      "command": "open",
      "args": ["-a", "Slack", "--args", "--remote-debugging-port={port}"],
      "startupTimeoutMs": 30000
    }
  },
  "timeouts": {
    "navigationTimeout": 60000,
    "defaultTimeout": 5000,
    "settle": 500
  },
  "network": {
    "allowedOrigins": ["example.com", "trusted-site.com"],
    "blockedOrigins": ["ads.example.com"]
  }
}

Available Options:

• browser.browserName: Browser to use (chromium, firefox, webkit)
• browser.launchOptions.headless: Run browser in headless mode (default: true on Linux without display, false otherwise)
• browser.launchOptions.channel: Browser channel (chrome, chrome-beta, msedge, etc.)
• browser.cdpEndpoint: Attach to an already-running Chromium-family app with CDP enabled
• browser.cdpHeaders: Map of HTTP headers to send with the CDP connect request, e.g. { "Authorization": "Bearer <token>" }, for endpoints that require header-based authentication
• browser.cdpTimeout: Maximum time in milliseconds to wait when connecting to the CDP endpoint (default: 30000)
• browser.cdpLaunch: Launch a Chromium-family desktop app with CDP enabled, wait for the endpoint, and manage the child process lifecycle
• CDP attach modes preserve the target browser's existing default-context settings instead of applying Playwright's defaults.
• browser.contextOptions.storageState: Start each session from a recorded Playwright storage state; applied in every mode except --extension (fresh contexts receive it at creation, reused contexts via setStorageState()). Sessions that share one reused context (non-isolated CDP modes) get the state applied once per context — a session joining a live context inherits its current state, not a fresh copy of the file; see Auditing pages behind a login
• timeouts.navigationTimeout: Maximum time for page navigation in milliseconds (default: 60000)
• timeouts.defaultTimeout: Default timeout for Playwright operations in milliseconds (default: 5000)
• timeouts.settle: How long to wait after every action before responding (default: 500). An action that finishes quietly is first watched for up to 100ms (or the settle delay, whichever is shorter) so scheduled network work can still be awaited before the settle delay.
• network.allowedOrigins: List of origins to allow (blocks all others if specified)
• network.blockedOrigins: List of origins to block
• outputDir: Directory for output files — reports, screenshots, traces, and session logs (CLI: --output-dir, env: PLAYWRIGHT_MCP_OUTPUT_DIR). Defaults to a fresh directory under the system temp folder, resolved once per server run so all of a run's artifacts land together. The output location is always server configuration; the deprecated MCP roots capability (client workspace folders) is no longer consulted.

CLI equivalents are also available: --cdp-launch-command, --cdp-launch-args, --cdp-launch-cwd, --cdp-launch-port, --cdp-launch-startup-timeout, --cdp-endpoint, --cdp-header (repeat for multiple headers, e.g. --cdp-header "Authorization: Bearer <token>"), and --cdp-timeout. The CDP headers and timeout can also be set via the PLAYWRIGHT_MCP_CDP_HEADERS (one Name: Value entry per line) and PLAYWRIGHT_MCP_CDP_TIMEOUT environment variables.

Use --timeout-settle or PLAYWRIGHT_MCP_TIMEOUT_SETTLE to override the post-action settle delay. It applies after every action so delayed DOM-only updates are included in the response; a short observation window also catches scheduled requests and waits for them before that delay.

HTTP Heartbeat

When the server runs with --port, it sends MCP heartbeat pings for Streamable HTTP sessions. Set PLAYWRIGHT_MCP_PING_TIMEOUT_MS to override the default 5000 ms timeout. Set it to 0 or any negative value to disable heartbeat pings for clients or proxies that do not answer server-initiated pings. A client that answers ping with a JSON-RPC "method not found" error (as clients on the MCP 2026-07-28 revision do) is treated as alive: the server stops heartbeating that session instead of closing it. Only an unanswered ping (timeout) or a transport failure closes the session.

Clients without the initialize handshake

Clients on the MCP 2026-07-28 revision no longer send the initialize handshake. With --port, requests carrying the revision's per-request _meta envelope are served natively on the 2026-07-28 protocol: server/discover is answered (so clients negotiating with versionNegotiation: 'auto' or a 2026-07-28 pin connect directly), results carry resultType and the SEP-2549 cache fields — the tool list is advertised as cacheable for one hour with cacheScope: "private" — and the SEP-2243 standard headers (MCP-Protocol-Version, Mcp-Method, Mcp-Name) are validated against the request body. Older handshake-free clients (2025-era requests without the envelope) are served statelessly as before. In both cases requests receive no heartbeat pings, and in the modes where the server creates browser contexts itself each request runs against a fresh default browser session: with the default persistent profile the per-request default context runs in its own disposable profile (like an explicit browser session), so parallel handshake-free requests do not contend for the stable profile — and the stable profile's sign-in state is not visible to them — while --isolated, remote endpoints and isolated CDP modes mint a fresh context per request anyway. Modes that reuse one live browser context are the exception: --extension (and a browser_connect or VS Code session switched to a connected-browser provider) and CDP attach without --isolated serve every handshake-free request from the same shared context, so its tabs, cookies and storage persist across requests — the same sharing that makes these modes refuse browser_session_open (in --vscode serving the session tools are the exception: they are host-scoped and keep running against the default provider even while switched — see Browser Session Tools). With a pinned --cdp-launch-port, only one launched application can be served at a time, so a second handshake-free request arriving while another request's browser context is still live is rejected with a clear error instead of silently attaching to the first request's application. With --user-data-dir, each handshake-free request launches a browser in the one configured profile: the profile's state persists across requests, and parallel requests contend for its browser lock and can fail with "Browser is already in use". Elsewhere, browser state that must persist across handshake-free requests belongs in an explicit browser session — a browserSessionId handle minted by browser_session_open in one request resolves in later ones (see Browser Session Tools). Clients that do send initialize keep the classic Mcp-Session-Id session behavior unchanged. When several such stateful clients are connected at once in the default persistent-profile mode, the first client's default context holds the stable profile — concurrent clients' default contexts run in their own disposable profiles (without the stable profile's sign-in state) until it is freed, instead of failing with "Browser is already in use".

Auditing pages behind a login

Most real audits target pages that only exist for a signed-in user. There are two ways to get there.

Interactive route (no setup)

Every tool shares one browser context, and audit_site crawls in a temporary tab of that same context, so cookies and local storage created while you drive the browser are already available to the crawl:

1. browser_navigate to the login page
2. browser_fill_form / browser_click to sign in
3. browser_navigate to the first page you want audited
4. audit_site — the crawl inherits the session you just created

This works out of the box in every mode, including the default persistent-profile mode. With the default profile the session also survives across server restarts, so you usually only sign in once. The default profile is keyed to the server's working directory, so each workspace's server keeps its own sign-in state — servers launched for different workspaces neither share cookies nor contend for the same profile.

Storage state route (repeatable, CI-friendly)

Record a session once with Playwright's codegen, then hand the file to the server:

npx playwright@1.63.0-alpha-2026-08-22 codegen --save-storage=auth.json https://example.com/login

Sign in in the opened browser, then close it — auth.json now holds the cookies and local storage.

Pass it to the server with the CLI flag, the environment variable, or the config file:

npx mcp-accessibility-scanner --isolated --storage-state ./auth.json

PLAYWRIGHT_MCP_ISOLATED=true PLAYWRIGHT_MCP_STORAGE_STATE=./auth.json npx mcp-accessibility-scanner

{
  "browser": {
    "isolated": true,
    "contextOptions": {
      "storageState": "./auth.json"
    }
  }
}

Every supported mode handles the state — by applying it or refusing it.

• Fresh-context modes (--isolated, the remote-endpoint mode, or either CDP mode combined with --isolated): the context is created with the storage state directly.
• Default persistent-profile mode with --storage-state: the session runs in a fresh, disposable profile — unique to that session and removed when it closes — built from the state, so the recorded state is provably the only session data (without --storage-state the regular persistent profile is used and survives restarts, as before). Any page the launch opened (for example from a URL in browser.launchOptions.args) is parked on a blank replacement before the state lands, then the replacement is navigated to the same URL, so a still-running anonymous page cannot overwrite the recorded identity and a scan never reads its DOM. This also means --storage-state cannot be combined with --user-data-dir (a user-supplied profile carries its own session and will not be wiped; the server refuses the combination).
• CDP modes without --isolated: the state is installed into the browser's existing context with Playwright's setStorageState(). Cookies are fully reset; origin storage (localStorage/IndexedDB) is reset for the origins recorded in the state plus any origins the Playwright connection has already seen — including pages open in the attached browser at connect time, whose storage can therefore be cleared even when the state omits them. Only origins from the profile's earlier history that this connection never saw survive untouched — cut in both directions, so treat an attached browser's storage as neither fully preserved nor fully reset, and add --isolated when you need a clean, fully-defined session. Pages already open in the attached browser are replaced with fresh tabs navigated to the same URLs so a scan never sees the previous identity's UI — and the old pages close before the state is installed, because a still-running page could otherwise persist the previous identity back into the freshly applied cookies or localStorage, which no later tab replacement could undo. A fresh tab also starts with empty per-tab sessionStorage (which sits outside Playwright storage states and would survive an in-place reload, where the old page's own scripts could even write the previous identity back between a clear and the reload), a replacement that fails to load is left blank or closed rather than left on a stale document, and these navigations run under a configured --allowed-origins/--blocked-origins policy just like every later navigation. The state is applied once per shared context: concurrent MCP sessions attached without --isolated share the browser's context, so a session joining while another is active inherits that context's live state (including anything the first session changed or cleared) rather than a fresh copy of the recorded file — add --isolated when every session must start from the recorded baseline.
• --extension (with or without --isolated) is the one exception: it works through the browser you are already running, where wiping cookies to install a recorded state is not an acceptable side effect, so the server refuses to start rather than doing that silently. There, sign in interactively instead — the persistent profile also keeps the session across restarts.

Keep the crawl from destroying its own session

audit_site excludes logout|signout by default, which is not enough for most applications. Add anything else that ends or changes the session before you start the crawl:

{
  "excludePathPatterns": ["logout|signout", "account/(close|delete)", "sessions/revoke", "/switch-(locale|account|org)"]
}

Note that excludePathPatterns replaces the default rather than extending it, so repeat logout|signout in your list.

If a session cookie disappears anyway, audit_site says so instead of reporting a confident, wrong audit: the result starts with a WARNING: cookie(s) … disappeared while loading <url> line, and both the JSON report and the structured content carry a sessionLosses list naming, for each lost cookie, the page that dropped it — the page reached after any redirect, and reported even when that page failed to finish loading. If one of the lost cookies was the session, every page scanned after that point was audited as a signed-out user — exclude the offending URL, sign in again, and re-run.

The check compares which cookies the crawled URLs carry, not their values, so a rotating CSRF token never reads as a lost session. A cookie the browser deleted at its own stated expiry is ignored for the same reason — Cloudflare's __cf_bm lives 30 minutes and would otherwise warn on any longer crawl. Beyond that no attempt is made to tell an authentication cookie from any other: nothing in a cookie marks it as one, so any cookie the crawl started with and later lost is reported. Monitoring does not stop at the first loss — each cookie is reported once, at the URL where it vanished, so an analytics cookie expiring early cannot mask the session cookie being dropped later. URLs discovered mid-crawl join the cookie tracking before they are visited, so a session cookie scoped to a path below the start URL (say /app) is watched too.

Available Tools

The MCP server provides comprehensive browser automation and accessibility scanning tools:

Core Accessibility Tool

scan_page

Performs a comprehensive accessibility scan on the current page using Axe-core.

Parameters:

• violationsTag: Array of WCAG/violation tags to check
• includeIncomplete (default true): also report Axe "incomplete" results
• maxNodesPerViolation (default 10): cap on nodes reported per rule
• includeSelectors / excludeSelectors: CSS selectors that scope the scan
• withRules / disableRules: Axe rule ids that narrow which rules run
• annotateScreenshot (default false): capture an annotated screenshot of the violations

Annotated screenshots: When annotateScreenshot is true, each violating element is outlined and labelled with the rule ids it failed, a full-page PNG is written to the MCP output directory (scan-page-annotated-{timestamp}-{token}.png) and returned as a resource link, and the markers are then removed so the page is left exactly as it was. The markers are drawn in an out-of-flow overlay clipped to each element's own box, so they never reflow the page. The overlay uses a fresh id per scan, is placed in the browser's top layer so it stays visible over an open dialog, popover or fullscreen element, and compensates for a CSS zoom or a scaled ancestor so markers line up with what is rendered. An element that fails several rules gets one box listing every rule id, and elements inside open shadow roots are marked by walking the shadow path Axe reports. Running animations are paused before the elements are measured and resumed after the capture, so a moving target keeps its marker. The markers themselves live in a shadow root under an overlay whose own styles are !important, so page CSS cannot restyle or hide what the report counts, and each rule label sits outside the clipped box so it stays readable on an element smaller than its own label. At most 50 elements are annotated per scan. The result text always reports how many nodes were marked out of the total, plus how many were left out because they exceeded the limit, were hidden, zero-size or off-canvas (a full-page screenshot is clipped to the document box), or were inside an iframe (cross-frame selectors cannot be resolved from the top document).

Supported Violation Tags:

• WCAG standards (in the default set): wcag2a, wcag2aa, wcag2aaa, wcag21a, wcag21aa, wcag21aaa, wcag22a, wcag22aa, wcag22aaa
• Section 508 (in the default set): section508
• Categories (opt-in): cat.aria, cat.color, cat.forms, cat.keyboard, cat.language, cat.name-role-value, cat.parsing, cat.semantics, cat.sensory-and-visual-cues, cat.structure, cat.tables, cat.text-alternatives, cat.time-and-media
• Non-conformance tags (opt-in): best-practice, experimental (see the caveat below -- a few experimental rules also carry a WCAG tag and run by default)

The default set is the WCAG and Section 508 tags only, so a default report means "this fails a conformance criterion". Category tags are opt-in for that reason: Axe matches requested tags with OR, so asking for cat.keyboard also pulls in best-practice rules such as region and skip-link that carry both tags. No live conformance rule is lost by leaving them out: the only rules reachable only through a cat.* tag are duplicate-id and duplicate-id-active, which Axe marks deprecated because WCAG removed SC 4.1.1. Add best-practice (landmark structure, heading order, tabindex hygiene) or a cat.* tag when you want that broader review.

The same OR semantics apply to experimental, with one deliberate exception: five experimental rules -- css-orientation-lock (SC 1.3.4), label-content-name-mismatch (SC 2.5.3), p-as-heading, table-fake-caption and td-has-header (SC 1.3.1) -- also carry a wcag* tag and so run in the default set. In Axe, experimental describes how settled the heuristic is, not whether the criterion is real, so these are kept rather than filtered out. Adding the experimental tag pulls in the remaining experimental rules, which have no conformance tag of their own.

Scan scoping: scan_page, audit_site, and scan_page_matrix accept includeSelectors and excludeSelectors to limit what Axe looks at. Use includeSelectors to audit one component (["#checkout-form"]) and excludeSelectors to drop third-party noise that pollutes every report (["#cookie-banner", "iframe.intercom-frame"]). Exclusions are applied after inclusions, so you can carve a widget out of an included subtree.

Selectors are resolved before the scan runs:

• Syntactically invalid CSS fails the scan, naming the selector.
• An includeSelectors entry that matches nothing fails the scan. Axe on its own would accept a partly-matching include set and quietly scan less than you asked for, so the scanner refuses rather than returning a clean-looking report with half the scope missing.
• An excludeSelectors entry that matches nothing is a no-op, not an error -- a crawl legitimately visits pages that lack the excluded widget.

In audit_site, selectors apply to every crawled page, so an includeSelectors value that is absent from a given page marks that page as errored in the report while the crawl continues. Link discovery runs before the scan, so pages reachable only through an errored page are still crawled.

Rule-level control: scan_page, audit_site, and scan_page_matrix accept withRules and disableRules to pick individual Axe rules instead of whole tag sets. Use withRules to re-check one rule after a fix (["color-contrast"]) and disableRules to mute a rule you have already triaged (["region"]). Rule ids are the ones Axe reports (image-alt, color-contrast, ...); see the Deque rule reference.

• withRules overrides violationsTag. Axe can run either a rule list or a tag list, never both, so when withRules is set the tags are ignored entirely -- withRules: ["image-alt"] runs exactly that one rule regardless of violationsTag. Rule ids are the more specific request, so they win.
• disableRules subtracts from whatever is selected. It applies to violationsTag and withRules alike. (Axe itself ignores disabled rules once you give it an explicit rule list; the scanner subtracts them up front so the two options mean the same thing together as apart.) Disabling every rule in withRules is an error rather than an empty scan.
• An explicitly empty withRules is an error too. withRules: [] selects no rules, and silently falling back to the tag set would run a different scan than the one requested — omit the option to scan by tags instead. Clients that build the list dynamically should drop the key when the list comes out empty.
• Unknown rule ids fail the scan, naming the id. Both options are checked against Axe's rule catalogue before the browser is touched, so a typo is reported as Unknown Axe rule id(s) in withRules: image-altt rather than surfacing later as an frame.evaluate failure from inside the page. Rule ids apply to a whole run, so audit_site and scan_page_matrix check them once before they touch the page -- a bad id fails the call outright instead of crawling every URL, or reloading and re-emulating the page, before rejecting the argument.

audit_site and scan_page_matrix record both values in their JSON report metadata, so a stored report can be told apart from a full scan.

Incomplete ("needs review") results: Axe returns incomplete for checks it cannot decide on its own -- contrast over a background image or gradient, ambiguous labels, elements it could not fully evaluate. scan_page, audit_site, and scan_page_matrix report these in a section separate from violations so you can resolve them by inspecting the page (screenshot, snapshot, browser_evaluate). Set includeIncomplete: false to suppress them.

Frames that could not be scanned: Axe is installed into every frame of the page before the scan runs. A frame that navigates mid-injection, or whose renderer does not answer within a second, is left out -- and its contents then contribute no findings. Rather than let that pass as a clean result, all three scan tools print a WARNING: Axe could not be installed in N frame(s) block listing the frame URLs, and audit_site and scan_page_matrix also record them per page and per variant in their JSON reports (unscannedFrames) and in structuredContent. A frame that was still loading usually succeeds on a re-run; one that fails consistently has to be audited on its own.

A nested frame is reported when any frame above it went unscanned, even if its own injection succeeded: Axe reaches a nested document only by relaying through the frames above it, so an outer frame without Axe takes everything below it out of the scan.

A frame you scoped out yourself is not reported: with excludeSelectors: ["iframe.intercom-frame"] that widget failing to load is the outcome you asked for, not a gap. Scope is resolved through the whole frame chain and across shadow boundaries, so an includeSelectors entry naming an ancestor still covers frames nested several levels below it or inside a shadow root, and excluding an outer frame or a shadow host silences everything inside it. Anything the check cannot resolve is reported rather than hidden.

Audit Tools

audit_site

Crawls and scans multiple internal pages, then aggregates violations across the site.

• Default strategy: link-based BFS from the current URL
• Supports links, nav, sitemap, and provided URL strategies
• Always writes a JSON report (default filename: audit-site-{timestamp}-{token}.json)
• Warns and records sessionLosses if the crawl loses cookies it started with — see Auditing pages behind a login

Example flow:

1. Navigate to your site homepage with browser_navigate
2. Run audit_site with maxPages: 25 and maxDepth: 2
3. Review the report path returned by the tool (written to the MCP output directory)

scan_page_matrix

Runs Axe scans on the same page across viewport/media/zoom variants and compares deltas against baseline.

• Default variants: baseline, mobile, desktop, forced-colors, reduced-motion, zoom-200
• Supports custom variants and optional reload between variants
• Always writes a JSON report (default filename: scan-matrix-{timestamp}-{token}.json)
• JSON report and structured result schema v2 set baseline deltas to null when either scan left frames unscanned, because their coverage is not comparable

Example flow:

1. Navigate to a page state you want to validate
2. Run scan_page_matrix with defaults (or provide custom variants)
3. Review per-variant deltas and open the generated JSON report path

audit_keyboard

Audits real keyboard focus behavior by pressing Tab (and optional Shift+Tab) with practical heuristics.

• Checks skip links, focus visibility, focus jumps, and possible focus traps
• Checks target size against WCAG 2.2 SC 2.5.8 (checkTargetSize, default on)
• Checks that focus is not entirely obscured, WCAG 2.2 SC 2.4.11 (checkFocusObscured, default on)
• Optional issue screenshots (screenshotOnIssue)
• Always writes a JSON report (default filename: audit-keyboard-{timestamp}-{token}.json)

Limits of the WCAG 2.2 checks — these are heuristics, not a conformance verdict:

• Target size only inspects elements the tab order actually reaches, so pointer-only targets are never measured.
• Of the SC 2.5.8 exceptions, only spacing (a 24px-diameter circle centered on the target must reach neither another target's box nor another undersized target's circle) and inline (an inline-level target — inline, inline-block, inline-flex, … — inside surrounding sentence text, found by walking out through inline wrappers such as <strong> to the containing block) are evaluated. The user agent control, essential, and equivalent exceptions cannot be detected from the DOM, so a target relying on one of them is still reported and needs manual triage.
• Spacing neighbours use the same pointer-target rule as the focused element, so rendered :disabled controls are not counted as neighbours, and contenteditable regions are counted as targets on both sides.
• Target size uses the element's bounding box, so an inline target wrapped over several lines is measured as one union box rather than per line, and a target whose visible area is cut down by an overflow or clip-path ancestor is measured at its full unclipped size.
• SC 2.4.11 is the Minimum (AA) level: a focused element is only reported when every sampled point of its box is covered by other content. Partially covered focus passes here, and the stricter SC 2.4.12 (AAA) is not checked. It applies to every focus stop with a rendered box, including elements that are not pointer targets such as iframes.
• Coverage is measured by hit-testing sample points and then checking that the element hit actually paints (visible, non-zero opacity all the way up to the first wrapper shared with the focused element, non-transparent background or background image). A transparent click-catching overlay therefore does not count as obscuration, but a covering layer with pointer-events: none is never returned by hit testing and is missed. Semi-transparent overlays that still leave content legible are reported.

Example flow:

1. Navigate to the target page and let it fully load
2. Run audit_keyboard with maxTabs: 50
3. Review focus findings and open the generated JSON report path

audit_screen_reader

Audits what a screen reader actually announces, using the browser's own accessibility tree (page.ariaSnapshot) plus element geometry. No screen reader is installed or driven; this is a static reading of the exposed tree.

Checks (checkNames)

• missing-accessible-name: controls and images exposed with no accessible name (WCAG 4.1.2)
• uninformative-accessible-name: names such as "click here", "read more", "image" that mean nothing out of context (WCAG 2.4.4)
• filename-as-accessible-name: image alt text that is a file name, e.g. IMG_1234.jpg, DSC00123 (WCAG 1.1.1). Only images are checked: a link or button legitimately named after the file it downloads (logo.png) is not a defect.
• label-in-name-mismatch: the accessible name does not contain the visible label, which breaks voice control (WCAG 2.5.3). The visible label of <input type="submit|button|reset"> is read from its value, and a web component's label is read from its open shadow root.
• duplicate-accessible-name: sibling links with the same name that lead to different URLs (WCAG 2.4.4)

Check (checkReadingOrder)

• reading-order-mismatch: accessibility tree order (what is read) versus visual position (WCAG 1.3.2), i.e. order, flex-direction: row-reverse, absolute positioning

What it deliberately does not detect

• Reading order is only compared between siblings that form a single row or a single column. Genuine two-dimensional layouts (grid, CSS multi-column, wrapped flex) have no single correct linear order and are skipped rather than guessed.
• Elements are excluded from the reading-order comparison when they render no text, are aria-hidden, floated, position: fixed, off-canvas, or clipped to 1px, because their visual position is decoupled from source order by design. Tolerance: two boxes count as swapped only when they are fully separated along the compared axis (1px), and right-to-left containers are compared right-to-left.
• Duplicate names are only reported when the destinations differ and are observable, which today means resolved link URLs (/help and https://site/help are the same destination). Two Save submit buttons in one form are never called ambiguous, because nothing in the exposed tree says whether they do different things.
• Only elements the AI snapshot gives a ref are analyzed, and Playwright refs the elements that are visible and receive pointer events. A control that is announced but not interactable (pointer-events: none, some off-canvas widgets) is therefore skipped: without a ref it cannot be measured, so neither its aria-hidden state nor a selector to fix it can be established, and reporting it would mostly surface decorative aria-hidden icons.
• Heading levels and landmark structure are not checked; axe already reports those (heading-order, region, landmark-one-main), so use scan_page for them.
• Findings for names overlap with axe rules such as link-name, button-name and image-alt; this tool adds the quality checks (generic names, file names, label-in-name, duplicates) that axe cannot make.
• It reports the page as currently rendered. Content behind a collapsed panel or another viewport is judged in that state.

Bounds: maxElements (default 400) caps how many screen-reader-reachable accessibility tree elements are analyzed. The snapshot also refs aria-hidden subtrees, which no check reports, so measuring continues past them until the budget is filled with reachable elements (up to a hard ceiling of twice maxElements measured, so a page built mostly of hidden refs stays bounded). maxFindingsPerCheck (default 20) caps the findings listed per check. Both truncations are stated in the summary and the JSON report, and the full counts are always reported. Always writes a JSON report (default filename: audit-screen-reader-{timestamp}-{token}.json).

Example flow:

1. Navigate to the target page and let it fully load
2. Run audit_screen_reader (optionally raise maxElements for a large page)
3. Fix the reported elements by ref, then re-run to confirm

Navigation Tools

browser_navigate

Navigate to a URL.

• Parameters: url (string)
• Non-2xx main-document responses are shown as an HTTP status line in page state.

browser_navigate_back

Go back to the previous page.

browser_navigation_timeout

Set default navigation timeout for existing tabs.

• Parameters: timeout (in ms; 30000-300000)

browser_default_timeout

Set default operation timeout for existing tabs.

• Parameters: timeout (in ms; 30000-300000)

Page Interaction Tools

Documentation truncated — see the full README on GitHub.