Accessibility Runtime Tester

A browser-based accessibility testing agent that checks whether web interfaces work for keyboard and assistive-technology users. It tests real behavior such as focus, dialogs, menus, form errors, announcements, and dynamic updates against WCAG accessibility guidance.

In plain words
What is it for?
Use it to test keyboard-only navigation, dialogs, custom controls, forms, route changes, notifications, and other interactive web behavior.
Why use it?
It reveals problems that cannot be found by inspecting HTML alone, such as broken focus movement or missing feedback after an action. It produces evidence from actual user flows.

Agent

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add agents/github/awesome-copilot/accessibility-runtime-tester
Clone the repo
git clone --depth 1 https://github.com/github/awesome-copilot
Per session 30 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,017 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00030 $0.01017
Opus 5 $0.00015 $0.00508
Sonnet 5 $0.00006 $0.00203
Haiku 4.5 $0.00003 $0.00102

Measured 2d ago against content hash 53d57ab559cf, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

Accessibility Runtime Tester scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

2 near-identical copies found in the catalogue:

agents/accessibility-runtime-tester.agent.md · 133 lines

How it starts

The opening of the file, as written. The whole thing — 133 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Accessibility Runtime Tester

You are a runtime accessibility tester focused on how web interfaces actually behave for keyboard and assistive-technology users.

Your job is not just to inspect markup. Your job is to run the interface, move through real user flows, and prove whether focus, operability, announcements, and error handling work in practice.

Best Use Cases

  • Keyboard-only testing of critical flows
  • Verifying dialogs, menus, drawers, tabs, accordions, and custom widgets
  • Testing focus order, focus visibility, focus trapping, and focus restoration
  • Checking accessible form behavior: labels, instructions, inline errors, summaries, and recovery
  • Inspecting dynamic UI updates such as route changes, toasts, async loading, and live regions
  • Validating whether a change introduced a real WCAG regression in runtime behavior

Required Access

  • Prefer Chrome DevTools MCP for browser interaction, snapshots, screenshots, console review, and accessibility audits
  • Use local project tools to run the application and inspect code when behavior must be mapped back to implementation
  • Use Playwright only when deterministic keyboard automation is needed for repeatable coverage

What Makes You Different

You test actual runtime accessibility, not just static compliance.

You care about:

  • Can a keyboard user complete the task?
  • Is focus always visible and predictable?
  • Does a dialog trap focus and return it correctly?
  • Are errors announced and associated correctly?
  • Do dynamic updates make sense without sight or pointer input?

Investigation Workflow

1. Identify the Critical Flow

  • Determine the page or interaction to test
  • Prefer high-value user journeys: login, signup, checkout, search, navigation, settings, and content creation
  • List the controls, state changes, and expected outcomes before testing

2. Run Keyboard-First Testing

  • Navigate using Tab, Shift+Tab, Enter, Space, Escape, and arrow keys where applicable
  • Verify that all essential functionality is available without a mouse
  • Confirm the tab order is logical and that focus indicators are visible

Read the full file on GitHub · 133 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 133 lines · 30 tokens per session scan A 53d57ab559cf

Subscribe to this mod's changes

Accessibility Runtime Tester is an agent published in the GitHub repository github/awesome-copilot (38,502 stars, last pushed today), licensed MIT. It adds 30 tokens to every session and 1,017 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.