ast-skeletonizer

ast-skeletonizer is a skill for Claude Code from alivirgo/Major-AI-Skills. It costs 25 tokens per session (1,259 once invoked), scanned A, original, MIT.

A code-reading method that keeps imports, types, classes, interfaces, and function signatures while removing implementation bodies. It uses an abstract syntax tree, a structured representation of source code, to make a compact map of a codebase.

In plain words
What is it for?
Use it when an agent needs to understand repository architecture, dependencies, or public APIs before changing code.
Why use it?
An agent can see the codebase's structure and available APIs without filling its context with implementation details and repeated boilerplate.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: mentions Codex.

Part of the major-ai-skills plugin — 147 skills, 8 plugins shipped together

Good fit Use it when an agent needs to understand repository architecture, dependencies, or public APIs before changing code.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/alivirgo/major-ai-skills/ast-skeletonizer
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.

Any agent
npx skills add alivirgo/Major-AI-Skills --skill ast-skeletonizer
Clone the repo
git clone --depth 1 https://github.com/alivirgo/Major-AI-Skills

Made for: Claude Code.

Or install major-ai-skills, the plugin that ships this one along with the rest of its 147 skills, 8 plugins.

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 ast-skeletonizer

README.md
[![agentmods](https://agentmods.dev/badge/skills/alivirgo/major-ai-skills/ast-skeletonizer/github.svg)](https://agentmods.dev/skills/alivirgo/major-ai-skills/ast-skeletonizer)
Your own site
<a href="https://agentmods.dev/skills/alivirgo/major-ai-skills/ast-skeletonizer"><img src="https://agentmods.dev/badge/skills/alivirgo/major-ai-skills/ast-skeletonizer/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.

agentmods 80×15 button for ast-skeletonizer

Your own site · 80×15
<a href="https://agentmods.dev/skills/alivirgo/major-ai-skills/ast-skeletonizer"><img src="https://agentmods.dev/badge/skills/alivirgo/major-ai-skills/ast-skeletonizer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 25 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,259 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00025 $0.01259
Opus 5 $0.00013 $0.00629
Sonnet 5 $0.00005 $0.00252
Haiku 4.5 $0.00003 $0.00126

Measured yesterday against content hash 6a8a1a5619f8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

ast-skeletonizer 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 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.

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.

skills/ast-skeletonizer/SKILL.md · 145 lines

How it starts

The opening of the file, as written. The whole thing — 145 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AST Code Skeletonization (Signature-Only Context Ingestion)

Overview

When an autonomous coding assistant needs to understand a repository's architecture, dependencies, or available APIs, ingesting full implementation files burns tens of thousands of tokens on internal loops, private variable assignments, and boilerplate logic.

The AST Code Skeletonization Protocol parses source code into an Abstract Syntax Tree and strips all function and method bodies - retaining only imports, type definitions, interface contracts, class signatures, and exported method headers.

This generates an ultra-high-density structural map that reduces context token consumption by 80% to 90% while preserving 100% of the API surface.


Full File vs. Skeletonized Signature Map

┌─────────────────────────────────────────────────────────────┐
│                 AST Skeletonization Mapping                 │
│                                                             │
│  Full Implementation Ingestion (520 Tokens):                │
│  export class PaymentGateway {                              │
│    private apiKey: string;                                  │
│    constructor(config: GatewayConfig) {                     │
│      this.apiKey = config.apiKey;                           │
│      this.validateKey(this.apiKey);                         │
│      // 40 lines of internal setup & logging logic...       │
│    }                                                        │
│    async processCharge(req: ChargeRequest): Promise<Result> │
│      const payload = { amount: req.amount, cur: req.cur };  │
│      // 30 lines of HTTP retries, exponential backoffs...   │
│      return parseResponse(await fetch(...));                │
│    }                                                        │
│  }                                                          │
│                                                             │
│  AST Skeletonized Signature (65 Tokens - 87.5% Reduction):  │
│  export class PaymentGateway {                              │
│    constructor(config: GatewayConfig);                      │
│    async processCharge(req: ChargeRequest): Promise<Result>;│
│  }                                                          │
└─────────────────────────────────────────────────────────────┘

Read the full file on GitHub · 145 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. yesterday Changed · -13 tokens per session 6a8a1a5619f8
  2. 7d ago First seen · 145 lines · 38 tokens per session scan A 8da27eb4ee5d

Subscribe to this mod's changes

ast-skeletonizer is a skill published in the GitHub repository alivirgo/Major-AI-Skills (1 stars, last pushed today), licensed MIT. It adds 25 tokens to every session and 1,259 once invoked, about $0.0001 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 2026-09-05.

Related

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