What is capture-fixture?

A command that saves a real API response as a JSON test fixture. TDD, or test-driven development, means using tests to define and check expected behavior while building software.

Use it to identify a documented service endpoint, request its response, and save a readable fixture under the project's tests directory.

It gives tests stable example responses, including errors such as missing records and rate limits, instead of relying on a live service every time.

How Cladios34/mtg-mcp-server configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to Cladios34/mtg-mcp-server. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/Cladios34/mtg-mcp-server/main/.claude/skills/capture-fixture/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/Cladios34/mtg-mcp-server

Made for: Claude Code.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/cladios34/mtg-mcp-server/capture-fixture/github.svg)](https://agentmods.dev/skills/cladios34/mtg-mcp-server/capture-fixture)

Your own site

<a href="https://agentmods.dev/skills/cladios34/mtg-mcp-server/capture-fixture"><img src="https://agentmods.dev/badge/skills/cladios34/mtg-mcp-server/capture-fixture/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/cladios34/mtg-mcp-server/capture-fixture"><img src="https://agentmods.dev/badge/skills/cladios34/mtg-mcp-server/capture-fixture.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 20 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 573 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.

Origin 100% copy Near-identical to another mod 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.

Model	Per session	Once invoked
Fable 5.1	$0.00020	$0.00573
Opus 5	$0.00010	$0.00287
Sonnet 5	$0.00004	$0.00115
Haiku 4.5	$0.00002	$0.00057

Measured 9d ago against content hash d9121575c24c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

capture-fixture scanned grade A with 1 finding 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 9d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

2. **Make the request** using `curl` or `python -c` with httpx. Include required headers:

Origin

This is a copy

100% identical to capture-fixture — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.claude/skills/capture-fixture/SKILL.md · 56 lines

What it actually says

Capture Fixture

Capture a real API response and save it as a JSON fixture for TDD testing.

Usage

/capture-fixture <service> <description>

Examples:

/capture-fixture scryfall card lookup for Muldrotha
/capture-fixture spellbook combos for Muldrotha
/capture-fixture 17lands card ratings for LRW PremierDraft
/capture-fixture edhrec commander page for Muldrotha

Workflow

Identify the endpoint from docs/SERVICE_CONTRACTS.md based on the service and description.
Make the request using curl or python -c with httpx. Include required headers:
- Scryfall: User-Agent: mtg-mcp-server/<version> and Accept: application/json
- All others: Accept: application/json
Save the response to tests/fixtures/<service>/:
- Use a descriptive snake_case filename (e.g., card_muldrotha.json, search_sultai_commander.json, card_not_found.json)
- Pretty-print with jq . or python -m json.tool
- Create the directory if it doesn't exist
Capture error responses too — 404s, rate limits, etc. are valuable fixtures.
Show the user:
- The full URL hit
- The saved file path
- A brief summary of the response shape (top-level keys, array lengths)

Service Endpoints Quick Reference

Service	Base URL	Key Endpoints
scryfall	`https://api.scryfall.com`	`/cards/named?exact=`, `/cards/search?q=`, `/cards/{id}/rulings`
spellbook	`https://backend.commanderspellbook.com`	`/api/variants/?q=`, `/api/estimate-bracket/`
17lands	`https://www.17lands.com`	`/card_ratings/data?expansion=&format=`
edhrec	`https://json.edhrec.com`	`/pages/commanders/{slug}.json`, `/pages/cards/{slug}.json`

Rules

Never overwrite an existing fixture without asking first
Always pretty-print JSON
Respect rate limits — wait between requests if capturing multiple fixtures
EDHREC slugs: lowercase, hyphens for spaces, strip commas/apostrophes

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.

9d ago First seen · 56 lines · 20 tokens per session scan A d9121575c24c

Subscribe to this mod's changes

capture-fixture is a skill published in the GitHub repository Cladios34/mtg-mcp-server (0 stars, last pushed 1mo ago), licensed MIT. It adds 20 tokens to every session and 573 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). It is 100% identical to capture-fixture, differing in 0 lines, and is treated as a copy.

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mtg-mcp-server: Skill for Claude Code