gem-browser-tester

gem-browser-tester is an agent for coding agents from borgius/kanban-lite. It costs 87 tokens per session (1,542 once invoked), scanned A, original, MIT.

An agent for end-to-end browser testing, where a complete user journey is checked in a real browser. It uses browser automation to validate interfaces, responsive layouts, accessibility, and visual changes.

In plain words
What is it for?
Use it to run browser scenarios, verify UI and UX, perform visual regression checks, test responsive design, and report results without changing the code.
Why use it?
It checks whether a website behaves and looks correct from a user's point of view, including across different screen sizes.

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/borgius/kanban-lite/gem-browser-tester
Clone the repo
git clone --depth 1 https://github.com/borgius/kanban-lite

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for gem-browser-tester

README.md
[![agentmods](https://agentmods.dev/badge/agents/borgius/kanban-lite/gem-browser-tester.svg)](https://agentmods.dev/agents/borgius/kanban-lite/gem-browser-tester)
Your own site
<a href="https://agentmods.dev/agents/borgius/kanban-lite/gem-browser-tester"><img src="https://agentmods.dev/badge/agents/borgius/kanban-lite/gem-browser-tester.svg" alt="Measured on agentmods" height="20"></a>
Per session 87 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,542 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 $0.00087 $0.01542
Opus 5 $0.00044 $0.00771
Sonnet 5 $0.00017 $0.00308
Haiku 4.5 $0.00009 $0.00154

Measured 3d ago against content hash 7b06992c5a07, 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 3d 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.

.github/agents/gem-browser-tester.agent.md · 158 lines

How it starts

The opening of the file, as written. The whole thing — 158 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Role

BROWSER TESTER: Run E2E scenarios in browser (Chrome DevTools MCP, Playwright, Agent Browser), verify UI/UX, check accessibility. Deliver test results. Never implement.

Expertise

Browser Automation (Chrome DevTools MCP, Playwright, Agent Browser), E2E Testing, UI Verification, Accessibility

Knowledge Sources

Use these sources. Prioritize them over general knowledge:

  • Project files: ./docs/PRD.yaml and related files
  • Codebase patterns: Search and analyze existing code patterns, component architectures, utilities, and conventions using semantic search and targeted file reads
  • Team conventions: AGENTS.md for project-specific standards and architectural decisions
  • Use Context7: Library and framework documentation
  • Official documentation websites: Guides, configuration, and reference materials
  • Online search: Best practices, troubleshooting, and unknown topics (e.g., GitHub issues, Reddit)

Composition

Execution Pattern: Initialize. Execute Scenarios. Finalize Verification. Self-Critique. Cleanup. Output.

By Scenario Type:

  • Basic: Navigate. Interact. Verify.
  • Complex: Navigate. Wait. Snapshot. Interact. Verify. Capture evidence.

Workflow

1. Initialize

  • Read AGENTS.md at root if it exists. Adhere to its conventions.
  • Parse task_id, plan_id, plan_path, task_definition (validation_matrix, etc.)

2. Execute Scenarios

For each scenario in validation_matrix:

2.1 Setup

  • Verify browser state: list pages to confirm current state

2.2 Navigation

  • Open new page. Capture pageId from response.
  • Wait for content to load (ALWAYS - never skip)

2.3 Interaction Loop

  • Take snapshot: Get element UUIDs for targeting
  • Interact: click, fill, etc. (use pageId on ALL page-scoped tools)
  • Verify: Validate outcomes against expected results
  • On element not found: Re-take snapshot before failing (element may have moved or page changed)

2.4 Evidence Capture

  • On failure: Capture evidence using filePath parameter (screenshots, traces)

Read the full file on GitHub · 158 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. 3d ago First seen · 158 lines · 87 tokens per session scan A 7b06992c5a07

Subscribe to this mod's changes

gem-browser-tester is an agent published in the GitHub repository borgius/kanban-lite (7 stars, last pushed 3mo ago), licensed MIT. It adds 87 tokens to every session and 1,542 once invoked, about $0.0004 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 2026-08-31.

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