Borrowing it
Nothing to install: this file belongs to claude-world/claude-101. 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/claude-world/claude-101/main/.claude/skills/claude-101-mastery/SKILL.mdgit clone --depth 1 https://github.com/claude-world/claude-101Wrote 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/skills/claude-world/claude-101/claude-101-mastery)<a href="https://agentmods.dev/skills/claude-world/claude-101/claude-101-mastery"><img src="https://agentmods.dev/badge/skills/claude-world/claude-101/claude-101-mastery/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/skills/claude-world/claude-101/claude-101-mastery"><img src="https://agentmods.dev/badge/skills/claude-world/claude-101/claude-101-mastery.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 | $0.00055 | $0.02441 |
| Opus 5 | $0.00028 | $0.01221 |
| Sonnet 5 | $0.00011 | $0.00488 |
| Haiku 4.5 | $0.00006 | $0.00244 |
Grade B, and why
claude-101-mastery scanned grade B 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 12d 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.
Asks the agent to reveal its instructionsmediumSystem prompt leakage
Directions to print, repeat or translate the system prompt extract configuration the operator did not intend to expose.
Before executing any use case, load the relevant reference file for that domain. Each file contains the exact tool call parameters, field-by-field workflow, and output instructions: How it starts
The opening of the file, as written. The whole thing — 134 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Claude 101 Mastery
This skill provides the optimal workflow for 24 use cases powered by the claude-101 MCP server. Each use case follows the same pattern: call the MCP tool first to get structured data and computation, then use that data to produce a superior final output.
The claude-101 MCP server provides 27 tools (3 meta + 24 use-case tools) that perform real local computation — statistics, code analysis, SQL parsing, financial math, text analysis, and scoring — and return structured JSON.
Core Principle
Always call the MCP tool FIRST before writing the final output. The tool provides two things that enhance the quality of the response:
-
Methodology — structured frameworks, best practices, section templates, and checklists that guide the approach to each use case. Following these frameworks ensures a professional-grade result that covers all standard elements.
-
Computation — precise metrics (scores, rankings, statistics, parsed data) that the user cannot get from natural language generation alone. These numbers ground the response in verifiable data.
Never skip the tool call. Never attempt to compute statistics, parse structured data, or calculate financial metrics manually. The tool handles computation; the final writing and reasoning come from Claude.
Workflow Pattern
For every use case, follow these five steps:
- Identify the matching MCP tool from the mapping table below
- Call the tool with the user's input as parameters
- Read every field in the result — each exists for a reason
- Produce the final output informed by both the methodology and the computed data
- Present key metrics (scores, rankings, statistics) explicitly to the user
When the tool returns both a template/scaffold AND computed analysis, use the template as a structural guide (do not copy it verbatim) and weave the computed metrics into the final output. The combination of professional structure and precise data is what makes the output superior.
What ships with it
4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 12d ago First seen · 134 lines · 55 tokens per session scan B 5ae3ce904605
claude-101-mastery is a skill published in the GitHub repository claude-world/claude-101 (5 stars, last pushed 5mo ago), licensed MIT. It adds 55 tokens to every session and 2,441 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it B with 1 finding (asks the agent to reveal its instructions). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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