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ast-grep

ast-grep is a skill for Claude Code from xdg/xdg-claude. It costs 44 tokens per session (407 once invoked), scanned A, original, Apache-2.0.

A tool for finding and changing code by its structure rather than its exact text. That means it can recognize the same code even when spacing or formatting differs.

In plain words
What is it for?
Use it to search code patterns, rename functions or methods, rewrite imports, preview refactoring changes, and inspect the functions, types, and imports in a file or package.
Why use it?
It helps when ordinary text editing finds too many matches or cannot reliably identify the right code.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the context-efficient-tools plugin — 5 skills shipped together

not rated 20repo 6d ago A scan SkillSpector: pass 44 tokens original Apache-2.0

Good fit Use it to search code patterns, rename functions or methods, rewrite imports, preview refactoring changes, and inspect the functions, types, and imports in a file or package.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/xdg/xdg-claude/ast-grep
View source ↗ xdg/xdg-claude
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 xdg/xdg-claude --skill ast-grep
Clone the repo
git clone --depth 1 https://github.com/xdg/xdg-claude

Made for: Claude Code.

Or install context-efficient-tools, the plugin that ships this one along with the rest of its 5 skills.

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-grep

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/xdg/xdg-claude/ast-grep"><img src="https://agentmods.dev/badge/skills/xdg/xdg-claude/ast-grep.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 407 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00044 $0.00407
Opus 5.5 $0.00018 $0.00163
Sonnet 5.5 $0.00009 $0.00081
Haiku 4.5 $0.00004 $0.00041

Measured 2mo ago against content hash 61bf7cb2b608, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

ast-grep 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 2mo 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.

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.

context-efficient-tools/skills/ast-grep/SKILL.md · 40 lines

What it actually says

ast-grep

Default invocation:

ast-grep -l LANG -p 'PATTERN'                      # search
ast-grep -l LANG -p 'OLD' -r 'NEW'                 # preview rewrite
ast-grep -l LANG -p 'OLD' -r 'NEW' --update-all    # apply

-l is required -- auto-detect is unreliable. Interactive mode (-i) does not work from this harness.

Metavariables

  • $VAR -- one AST node (an expression, an identifier, ...)
  • $$$ARGS -- zero or more items in a list (function args, statement bodies)
  • $$STMT -- multiple statements

Canonical patterns

# Rename a function across all call sites
ast-grep -l typescript -p 'oldFn($$$ARGS)' -r 'newFn($$$ARGS)'

# Rename a method on any receiver
ast-grep -l javascript -p '$OBJ.oldMethod($$$ARGS)' -r '$OBJ.newMethod($$$ARGS)'

# Rewrite imports
ast-grep -l typescript -p 'import $WHAT from "old-pkg"' -r 'import $WHAT from "new-pkg"'

Workflow: run without -r to see matches, run with -r to preview the diff, then add --update-all. For surgical per-site control, use ast-grep to find locations and Edit to apply.

To list a file's or package's structure (functions, types, imports/exports) rather than match a pattern, use the outline subcommand -- see the code-structure skill.

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. 2mo ago First seen · 40 lines · 44 tokens per session scan A 61bf7cb2b608

Subscribe to this mod's changes

ast-grep is a skill published in the GitHub repository xdg/xdg-claude (20 stars, last pushed 6d ago), licensed Apache-2.0. It adds 44 tokens to every session and 407 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-08-30.

Debugging
Related

ast-grep compared with skills from other repositories

ast-grep next to 6 skills from other repositories
ModTypeStarsLast pushLicenceScanTokensWorks with
ast-grepxdg/xdg-claudeSkill206d agoApache-2.0A44Claude Code
systematic-debuggingopen-metadata/OpenMetadataSkill16kyesterdayApache-2.0A37Claude Code
log-error-digestzebbern/claude-code-guideSkill4.7k3d agoMITA71Claude Code, Codex
cwv-optimizeradobe/skillsSkill319yesterdayApache-2.0A112Claude Code
ci-fixersipyourdrink-ltd/bernsteinSkill1.2kyesterdayApache-2.0A15Claude Code, Codex
incident-response-incident-responsermyndharis/antigravity-skillsSkill1.9k23d agoMITA36Claude Code
triaging-web-analytics-supportPostHog/posthogSkill41kyesterdaynoneA151Claude Code, Codex