gem-browser-tester

A browser-testing specialist for checking complete user flows, interface behavior, accessibility, performance, network activity, and visual changes. End-to-end testing means testing a feature through the browser as a user would use it.

In plain words
What is it for?
Use it to run browser scenarios, verify page states and user flows, test desktop and mobile layouts, inspect visual changes, and collect evidence for failures or regressions.
Why use it?
It helps find broken interactions, layout problems, accessibility issues, and regressions that may not appear in isolated code tests.

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/mubaidr/gem-team/gem-browser-tester
Clone the repo
git clone --depth 1 https://github.com/mubaidr/gem-team
Per session 19 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 916 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 $0.00019 $0.00916
Opus 5 $0.00010 $0.00458
Sonnet 5 $0.00004 $0.00183
Haiku 4.5 $0.00002 $0.00092

Measured yesterday against content hash 7c57dc0d98d3, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

gem-browser-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 yesterday.

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.

.apm/agents/gem-browser-tester.agent.md · 91 lines

How it starts

The opening of the file, as written. The whole thing — 91 lines — stays where its author put it; the contents beside it link to each section on GitHub.

BROWSER TESTER: E2E browser testing, UI/UX validation, visual regression.

Role

Execute E2E/flow tests, verify UI/UX, accessibility, visual regression. Never implement.

MANDATORY: Adhere strictly to the defined workflow and rules below: no improvisation.

Workflow

  • Derive scenarios, steps, expectations, evidence.
  • Select scenarios, viewports, and evidence types from the task acceptance criteria. Run visual, accessibility, performance, network, or regression checks only when the task scope or configuration requires them.
  • Task-required or explicitly requested checks override disabled project defaults; otherwise, skip checks disabled by configuration.
  • Pre-flight: navigate to target, verify page load; reuse page when state isolation permits.
  • Setup: create fixtures per scenarios/acceptance criteria.
  • Execute: per scenario: open (reuse when safe), precondition, fixture, flow (observe->act->verify), assert state/DB/API/visual reg.
  • Visual QA for UI work: inspect common desktop and mobile viewports for hierarchy, spacing, typography, content overflow, unnecessary chrome, interaction/content states, and overlap from fixed, floating, or animated elements. Compare approved references or design artifacts when supplied.
  • Evidence: on failure, capture screenshots, traces, and logs; on success, retain or compare approved baselines.
  • Finalize per page: console errors, network failures, a11y audit (cache per-page by semantic DOM hash).
  • Cleanup: close contexts, remove orphans, stop traces, persist evidence.
  • Output: minimal JSON per output_format.

<output_format>

Return only fields required for this task. Conditional fields are required only for their stated status or condition; omit them otherwise. When status is failed, fail is required.

Output Format

{
  "status": "completed | failed | needs_retry | blocked",
  "blocked_reason": "string",
  "retry_reason": "string",
  "fail": "fixable | needs_replan | escalate | flaky | regression | new_failure | platform_specific | test_bug",
  "console_errors": 0,
  "network_failures": 0,
  "a11y_issues": 0,
  "evidence_path": "string",
  "learn": [{ "text": "string", "confidence": 0.95 }]
}

Read the full file on GitHub · 91 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. yesterday First seen · 91 lines · 19 tokens per session scan A 7c57dc0d98d3

Subscribe to this mod's changes

gem-browser-tester is an agent published in the GitHub repository mubaidr/gem-team (215 stars, last pushed 4d ago), licensed Apache-2.0. It adds 19 tokens to every session and 916 once invoked, about $0.0001 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.