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Web Application Testing

Toolkit for interacting with and testing local web applications using Playwright.

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Install this skill Read the source first Free Written by anthropics · unverified publisher
Context cost
5.6k tokensestimated from the bundle, loaded when it triggers
Bundle
6 files · 22.4 kB4 scripts among them — read before you run
Licence
Complete terms in LICENSE.txtfree to use
Last change
—no release on file
Servers it uses
Noneruns standalone

What it does

Toolkit for interacting with and testing local web applications using Playwright. Supports verifying frontend functionality, debugging UI behavior, capturing browser screenshots, and viewing browser logs.

Installed, it changes the agent in these ways.

What this skill changes about the agent is not written down here yet. The listing was collected from its source, and the description is in its own SKILL.md.

Workflow

Runs a procedure end to end.

securitytestingplaywright
Filed under

Security & Testing

The skill itself

This is the whole product. A skill is instructions the model reads, so there is nothing behind the listing you cannot see first — the front matter loads with every session, and the body below it loads when the skill triggers.

SKILL.md3.9 kB · 96 lines
--- name: webapp-testing description: Toolkit for interacting with and testing local web applications using Playwright. Supports verifying frontend functionality, debugging UI behavior, capturing browser screenshots, and viewing browser logs. license: Complete terms in LICENSE.txt ---
7# Web Application Testing
8
9To test local web applications, write native Python Playwright scripts.
10
11**Helper Scripts Available**:
12- scripts/with_server.py - Manages server lifecycle (supports multiple servers)
13
14**Always run scripts with --help first** to see usage. DO NOT read the source until you try running the script first and find that a customized solution is abslutely necessary. These scripts can be very large and thus pollute your context window. They exist to be called directly as black-box scripts rather than ingested into your context window.
15
16## Decision Tree: Choosing Your Approach
17
18```
19User task → Is it static HTML?
20 ├─ Yes → Read HTML file directly to identify selectors
21 │ ├─ Success → Write Playwright script using selectors
22 │ └─ Fails/Incomplete → Treat as dynamic (below)
23 │
24 └─ No (dynamic webapp) → Is the server already running?
25 ├─ No → Run: python scripts/with_server.py --help
26 │ Then use the helper + write simplified Playwright script
27 │
28 └─ Yes → Reconnaissance-then-action:
29 1. Navigate and wait for networkidle
30 2. Take screenshot or inspect DOM
31 3. Identify selectors from rendered state
32 4. Execute actions with discovered selectors
33```
34
35## Example: Using with_server.py
36
37To start a server, run --help first, then use the helper:
38
39**Single server:**
40```bash
41python scripts/with_server.py --server "npm run dev" --port 5173 -- python your_automation.py
42```
43
44**Multiple servers (e.g., backend + frontend):**
45```bash
46python scripts/with_server.py \
47 --server "cd backend && python server.py" --port 3000 \
48 --server "cd frontend && npm run dev" --port 5173 \
49 -- python your_automation.py
50```
51
52To create an automation script, include only Playwright logic (servers are managed automatically):
53```python
54from playwright.sync_api import sync_playwright
55
56with sync_playwright() as p:
57 browser = p.chromium.launch(headless=True) # Always launch chromium in headless mode
58 page = browser.new_page()
59 page.goto('http://localhost:5173') # Server already running and ready
60 page.wait_for_load_state('networkidle') # CRITICAL: Wait for JS to execute
61 # ... your automation logic
62 browser.close()
63```
64
65## Reconnaissance-Then-Action Pattern
66
671. **Inspect rendered DOM**:
68 ```python
69 page.screenshot(path='/tmp/inspect.png', full_page=True)
70 content = page.content()
71 page.locator('button').all()
72 ```
73
742. **Identify selectors** from inspection results
75
763. **Execute actions** using discovered selectors
77
78## Common Pitfall
79
80❌ **Don't** inspect the DOM before waiting for networkidle on dynamic apps
81✅ **Do** wait for page.wait_for_load_state('networkidle') before inspection
82
83## Best Practices
84
85- **Use bundled scripts as black boxes** - To accomplish a task, consider whether one of the scripts available in scripts/ can help. These scripts handle common, complex workflows reliably without cluttering the context window. Use --help to see usage, then invoke directly.
86- Use sync_playwright() for synchronous scripts
87- Always close the browser when done
88- Use descriptive selectors: text=, role=, CSS selectors, or IDs
89- Add appropriate waits: page.wait_for_selector() or page.wait_for_timeout()
90
91## Reference Files
92
93- **examples/** - Examples showing common patterns:
94 - element_discovery.py - Discovering buttons, links, and inputs on a page
95 - static_html_automation.py - Using file:// URLs for local HTML
96 - console_logging.py - Capturing console logs during automation
In the file
SKILL.md501 words
Files6
LicenceComplete terms in LICENSE.txt
Why you can read it

Nothing in a skill executes. The client loads the text and the model follows it, so a skill can be audited the way a runbook is — by reading it.

What it costs in context

Skills are not billed by the call. They are paid for in context: every token the instructions occupy is a token your code, your diff and your conversation cannot use. Here is what this one takes and when it takes it.

≈70
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
5,530
on trigger
The instruction body and 5 supporting files, read only when the skill fires.
2.8%
of a 200k window
Ten skills this size would take about 28% of the window before you open a file.
050k100k150k200k context window

5.6k tokens, estimated from the bundle at four bytes to the token, held for the rest of the session once it triggers. Heavy. Teams tend to install this one per project rather than globally, and load it only when the job comes up.

Servers bill, skills cost

A server charges by the month. A skill charges once per session, in context, and then keeps charging it for as long as the session lives.

Before and after

The same question, put to the same model twice: once as it comes, and once with these instructions loaded.

No worked example has been published for this skill yet.

Adoption
Installsnone yet
Ratingno reviews yet

The procedure it runs

The procedure has not been published here. It is in the skill’s own SKILL.md, which its author has not sent to the marketplace yet.

Prose, not code

These steps are written for a model to follow, not executed by a runtime. It can still be told to skip one, and it will say so when it does.

Servers it uses

None. This skill calls no MCP servers at all.

Everything it needs is in the instructions, so it works in a project with nothing connected — the model reads the file and changes how it works with what it can already reach.

It writes no files and reaches no network. All it changes is how the model reasons and writes.

What it asks for
Writes filesno
Network accessno

Read from the allowed-tools line of this skill’s own SKILL.md. A skill grants no permissions of its own — it can only ask for tools your client already has.

What it will not do

Every skill is narrow, and the useful ones say where they stop. These are the jobs this one is the wrong tool for.

What this skill is not for has not been published here. Nothing is implied by that: it is a section the author has not filled in.

What is in the bundle

6 files, 22.4 kB on disk. Mostly text — the instructions the model reads — with 4 scripts in it that your client would run only if the instructions tell it to.

  • examples/console_logging.py1.0 kB
  • examples/element_discovery.py1.5 kB
  • examples/static_html_automation.py1.0 kB
  • LICENSE.txt11.3 kB
  • scripts/with_server.py3.7 kB
  • SKILL.md3.9 kB
What is not in it

A skill installs nothing and depends on nothing: it is a folder your client reads. This one carries 4 scripts beside the text, so the bundle is 6 files you can review in full before installing. The Complete terms in LICENSE.txt licence covers the templates and examples as well as the instructions.

Install

Installing copies the bundle into your project. Nothing runs at install time — the files sit on disk until the model reads them.

# Web Application Testing · 5.6k tokens when loaded npx mcprush@latest skill add anthropics/web-application-testing

Writes to .claude/skills/web-application-testing/ in the current project. Add --global to put it in your home directory instead, for every project.

Which clients pick it up on their own

A skill is a folder of text. A client with a skills folder reads it without being told; everywhere else the same text works, it is just handed to the model rather than found.

Claude Code.claude/skills/
Claude Desktop
ChatGPT
Cursor.cursor/skills/
VS Code.github/skills/
Codex CLI.agents/skills/
Gemini CLI.gemini/skills/
Grok.grok/skills/
Zed.agents/skills/
Windsurf.windsurf/skills/
Agent SDK.claude/skills/
HTTP / API
This release
Versionnot versioned
Publishedno release date on file
PriceFree
Referenceanthropics/web-application-testing

Versions

Its author publishes no version number, so there is nothing here to pin to: what you install is the folder as it stands today. Instructions change more often than APIs do — a skill can be rewritten entirely without anything it depends on moving.

v
  • No earlier releases have been published to the marketplace.
Pinning

Nothing to pin to: this skill carries no version number of its own. What you install is what the folder holds on the day you install it.

Reviews

—no reviews yet · no installs yet

Nobody has reviewed this skill yet. The rating is the mean of the reviews written here, so there is none until somebody writes the first.

Who can post

Only accounts that have had the skill installed for fourteen days, so a review is written after living with it rather than after reading it. Publishers may reply once.

Who wrote it

AN
anthropics

Publishes on mcprush.

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