Borrowing it
Nothing to install: this file belongs to timothywarner-org/ab900. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/timothywarner-org/ab900/main/CLAUDE.mdgit clone --depth 1 https://github.com/timothywarner-org/ab900Wrote 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.
[](https://agentmods.dev/instructions/timothywarner-org/ab900/claude-md)<a href="https://agentmods.dev/instructions/timothywarner-org/ab900/claude-md"><img src="https://agentmods.dev/badge/instructions/timothywarner-org/ab900/claude-md/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.
<a href="https://agentmods.dev/instructions/timothywarner-org/ab900/claude-md"><img src="https://agentmods.dev/badge/instructions/timothywarner-org/ab900/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.06791 | $0.06791 |
| Opus 5.5 | $0.02716 | $0.02716 |
| Sonnet 5.5 | $0.01358 | $0.01358 |
| Haiku 4.5 | $0.00679 | $0.00679 |
Grade A, and why
ab900 CLAUDE.md scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
cat /tmp/urls.txt | xargs -P 5 -I{} sh -c 'echo "$(curl -s -o /dev/null -w "%{http_code}" -L --max-time 20 -A "Mozilla/5.0" "{}") {}"' | grep -v '^200' How it starts
The opening of the file, as written. The whole thing — 307 lines — stays where its author put it; the contents beside it link to each section on GitHub.
CLAUDE.md
This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
Repository Purpose
This is a content-only repository for an AB-900 certification study buddy powered by GitHub Copilot agents, the Pearson live-training course home, and the archived July 2026 O'Reilly edition. There is no application code, no build system, and no tests. The primary artifacts are agent definitions, skill specs, prompt templates, MCP server configurations, and distilled Microsoft Learn course content.
Architecture
.github/
agents/ab900-cert-buddy-agent.agent.md # Main Copilot agent definition
skills/ # ab900-item-creator, ab900-scenario-walkthrough, ab900-study-planner
prompts/ # Practice questions, scenario walkthrough, study planner
copilot-instructions.md # Copilot workspace instructions + rename table
CONTRIBUTING.md # Contribution guidance (GitHub shows it as a tab)
workflows/
course-home.yml # Pearson course-home check (blocking)
validate.yml # Terminology and style checks (non-blocking)
mlc-config.json # Markdown link checker config
.vscode/ # Study buddy MCP servers, extensions, settings
README.md, TUTORIALS.md, AGENTS.md, NOTICE.md, LICENSE # Pearson course home
docs/
certify.md # Optional AB-900 exam links and logistics
study-buddy.md # Study buddy setup and features
tenant-setup-guide.md # Lab tenant setup
evidence/ # Dated, observed instructor test runs
handouts/ # Pearson Resources-widget PDFs (byte-identical) + updates
images/ # banner.png, social-preview.png, brand.json
references/
ab900-objectives.md # AB-900 skills-measured reference
fictional-companies.md # Microsoft fictional company names for scenarios
style-guide.md # Microsoft Writing Style Guide key principles
scripts/ # Test-CourseHome.py, make_banner.py
starter-files/ # Synthetic Contoso files for the starter agent
archive/july-2026/ # The four-hour July 2026 O'Reilly edition
docs/ # module-01..06 notes, demo scripts, cheat sheets, opener
segment-01..04-*/ # Per-segment demos, labs, slide notes, resources
shared-resources/ # Exam guide, practice questions, scripts, templates
FAQ.md, QUICKSTART.md, lab-purview-dlp-15min.md
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.
- yesterday Changed · -40 lines · -1,319 tokens per session 48f0bf69025c
- 2d ago Changed · +2 lines · +233 tokens per session 5f9e02a0eaa8
- 8d ago Changed · +2 lines · +215 tokens per session 808bca64f5df
- 1mo ago First seen · 343 lines · 7,662 tokens per session scan A e67dd8e929e0
ab900 CLAUDE.md is an instructions file published in the GitHub repository timothywarner-org/ab900 (29 stars, last pushed today), licensed MIT. It adds 6,791 tokens to every session, about $0.0272 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other instructions, from other repositories
vscode buildNext.instructions.md
Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).
next.js AGENTS.md
AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.
vscode oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, cache eligibility and rollout and applying the notice (cutover).
langchain AGENTS.md
AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.
vscode copilot-instructions.md
Copilot instructions for microsoft/vscode, covering vs code copilot instructions, project overview, root folders, core architecture (src/ folder) and built-in extensions (extensions/ folder).
vscode model-prompts.instructions.md
Model-specific prompt authoring and registry guidelines.