Agent skill

Ast Grep

Write and debug ast-grep rules for structural code search and rewrite.

AGPL-3.0Auto-check passedDevelopment

Install Ast Grep

skills CLI

$ npx skills add BiFangKNT/mtga --skill ast-grep -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install BiFangKNT/mtga ast-grep --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/BiFangKNT/mtga.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.codex/skills/ast-grep .claude/skills/ast-grep && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "ast-grep" agent skill from https://github.com/BiFangKNT/mtga/tree/tauri/.codex/skills/ast-grep into .claude/skills/ast-grep/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ast-grep", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/BiFangKNT/mtga/tree/tauri/.codex/skills/ast-grep

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add BiFangKNT/mtga --skill ast-grep -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install BiFangKNT/mtga ast-grep --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/BiFangKNT/mtga.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.codex/skills/ast-grep .agents/skills/ast-grep && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "ast-grep" agent skill from https://github.com/BiFangKNT/mtga/tree/tauri/.codex/skills/ast-grep into .agents/skills/ast-grep/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ast-grep", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add BiFangKNT/mtga --skill ast-grep -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install BiFangKNT/mtga ast-grep --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/BiFangKNT/mtga.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.codex/skills/ast-grep .cursor/skills/ast-grep && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "ast-grep" agent skill from https://github.com/BiFangKNT/mtga/tree/tauri/.codex/skills/ast-grep into .cursor/skills/ast-grep/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ast-grep", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/BiFangKNT/mtga.git --path .codex/skills/ast-grep

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add BiFangKNT/mtga --skill ast-grep -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install BiFangKNT/mtga ast-grep --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/BiFangKNT/mtga.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.codex/skills/ast-grep .gemini/skills/ast-grep && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "ast-grep" agent skill from https://github.com/BiFangKNT/mtga/tree/tauri/.codex/skills/ast-grep into .gemini/skills/ast-grep/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ast-grep", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install BiFangKNT/mtga ast-grep

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add BiFangKNT/mtga --skill ast-grep -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/BiFangKNT/mtga.git skills-src && mkdir -p .github/skills && cp -r skills-src/.codex/skills/ast-grep .github/skills/ast-grep && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "ast-grep" agent skill from https://github.com/BiFangKNT/mtga/tree/tauri/.codex/skills/ast-grep into .github/skills/ast-grep/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ast-grep", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add BiFangKNT/mtga --skill ast-grep -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install BiFangKNT/mtga ast-grep --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/BiFangKNT/mtga.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.codex/skills/ast-grep .opencode/skills/ast-grep && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "ast-grep" agent skill from https://github.com/BiFangKNT/mtga/tree/tauri/.codex/skills/ast-grep into .opencode/skills/ast-grep/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ast-grep", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: ast-grep
GitHub stars: 1.2k
Token cost: ~802 tokens
SKILL.md length: 258 words
Files: 3 (incl. references)
Skills in repo: 6
Repo updated: Jun 18, 2026
First seen: Oct 7, 2026
Licence: AGPL-3.0

At a glance

Write and debug ast-grep rules for structural code search and rewrite.

Works in 4 steps: Understand the Query → Start with the Smallest Pattern → Escalate to YAML Rule for Structure Logic → …
Tasks require AST-aware matching (not plain text)
SKILL.md covers Overview, General Workflow, CLI Quick Reference and Tips for Writing Effective Rules, plus 1 more section
Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Ast Grep is an agent skill from BiFangKNT/mtga. Write and debug ast-grep rules for structural code search and rewrite. Use when tasks require AST-aware matching (not plain text), such as finding specific syntax shapes, relational patterns (inside/has), composite logic (all/any/not), or precise code refactors across a codebase.

Its SKILL.md is about 800 tokens, which your agent loads only when the skill is triggered. The skill folder holds 3 other files, including reference files (for example `references/rule_reference.md` and `references/windows.md`).

It sits in Development, covering Codebase onboarding and Refactoring. The repository describes itself as: 基于本地代理的方式，绕过 IDE 的固定模型服务商限制. The licence is AGPL-3.0.

When your agent uses it

Tasks require AST-aware matching (not plain text)
Such as finding specific syntax shapes
Relational patterns (inside/has)
Composite logic (all/any/not)

Example prompts

“/ast-grep”

Workflow steps

4 steps, taken from the step headings in SKILL.md.

Understand the Query
Start with the Smallest Pattern
Escalate to YAML Rule for Structure Logic
Validate and Search

What it can do on your machine

Read from SKILL.md and the folder at commit 72669fb. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md (its code samples are bash and yaml).
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Ast Grep loads about 802 tokens when it runs, and up to ~3.7k if it reads all its reference files. Until then it costs about 72 tokens; SKILL.md has 258 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~72
When it runs · the whole SKILL.md, loaded when a task matches: ~802
With references · SKILL.md plus every file in references/, read only if the agent opens them: ~3.7k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from BiFangKNT/mtga at commit 72669fb, republished under its AGPL-3.0 licence (© BiFangKNT). 258 words, ~802 tokens.

Download SKILL.mdSave it as .claude/skills/ast-grep/SKILL.md (or your agent's skills folder). This skill also uses 2 other files; get the full folder from GitHub.

name: ast-grep
description: Write and debug ast-grep rules for structural code search and rewrite. Use when tasks require AST-aware matching (not plain text), such as finding specific syntax shapes, relational patterns (inside/has), composite logic (all/any/not), or precise code refactors across a codebase.

ast-grep Code Search

Overview

Translate user intent into sg patterns/rules, validate quickly, then run against target scope.

General Workflow

Step 1: Understand the Query

Pin down:

target syntax shape
language
file scope
include/exclude constraints

Step 2: Start with the Smallest Pattern

Use sg run --pattern first.

bash

sg run --pattern 'console.log($ARG)' --lang javascript src

Step 3: Escalate to YAML Rule for Structure Logic

For relational/composite logic (inside / has / precedes / follows / all / any / not / matches), use sg scan --rule.

yaml

# rule.yml
id: async-with-await
language: javascript
rule:
  kind: function_declaration
  has:
    pattern: await $EXPR
    stopBy: end

bash

sg scan --rule rule.yml src

Step 4: Validate and Search

Test on a tiny sample first, then search the project.

bash

echo "async function f(){ await g() }" | sg scan --rule rule.yml --stdin
sg scan --rule rule.yml src --json=compact

CLI Quick Reference

Inspect Code Structure (--debug-query)

Use when kind/pattern mismatch is unclear.

bash

sg run --pattern 'class $NAME { $$$BODY }' \
  --lang javascript \
  --debug-query=pattern

Test Rules (scan with --stdin)

bash

echo "const x = await fetch();" | sg scan --inline-rules "id: test
language: javascript
rule:
  pattern: await \$EXPR" --stdin --json=compact

Search with Patterns (run)

bash

sg run --pattern 'function $NAME($$$)' --lang javascript src --json=compact

Search with Rules (scan)

bash

sg scan --rule rule.yml src
sg scan --inline-rules "id: find-async
language: javascript
rule:
  kind: function_declaration
  has:
    pattern: await \$EXPR
    stopBy: end" src

Tips for Writing Effective Rules

Default to stopBy: end for Deep Searches

For relational rules (inside, has), default to:

yaml

has:
  pattern: await $EXPR
  stopBy: end

This ensures the search traverses the entire subtree rather than stopping at the first non-matching node.

Start Simple, Then Add Complexity

pattern
kind
add inside/has
add all/any/not

Metavariable Rules

Use exact metavariable forms only: $A, $$OP, $$$ARGS.
Keep metavariable text as the only content in its AST node.
If a rule depends on previously captured metavariables, combine sub-rules in all to guarantee match order.

No-Match Triage

Run with --json=compact.
If output is [], treat as no match and refine pattern/scope.
If stderr has parser/arg errors, fix language, pattern, or flags first.

Resources

references/

rule_reference.md: Full rule syntax (atomic, relational, composite, metavariables)
windows.md: PowerShell quoting/escaping tips and Vue SFC script-block workflow

Load only the reference needed for the current task.

Files

SKILL.md and 2 other files (references) in .codex/skills/ast-grep of BiFangKNT/mtga.

SKILL.md
references/rule_reference.md
references/windows.md

Open the folder on GitHubat commit 72669fb

Compare with similar skills

Ast Grep next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Ast Grep compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Ast Grep this skillBiFangKNT/mtga	1.2k	—	~802	Automated safety check: Pass	AGPL-3.0	3 mo ago
Lsp Code Analysislsp-client/lsp-skill	118	—	~3k	Automated safety check: Pass	MIT	8 mo ago
Gograph Go Repository Intelligenceozgurcd/gograph	228	—	~4.8k	Automated safety check: Notes	MIT	2 days ago
Ripwire Graph Queryredhat-et/ripwire	2.4k	—	~1.1k	Automated safety check: Notes	Apache-2.0	today
CodeNavitech-leads-club/agent-skills	7k	—	~3.4k	Automated safety check: Pass	CC-BY-4.0	yesterday
Golang Goplscontext-labs/whip	1.1k	1 repos	~2.3k	Automated safety check: Pass	MIT	4 days ago

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Questions about Ast Grep

What does Ast Grep do?

Write and debug ast-grep rules for structural code search and rewrite. Ast Grep is an agent skill from BiFangKNT/mtga. Write and debug ast-grep rules for structural code search and rewrite.

When should I use Ast Grep?

Ast Grep fits situations like: tasks require AST-aware matching (not plain text); such as finding specific syntax shapes; relational patterns (inside/has); composite logic (all/any/not).

How do I install Ast Grep in Claude Code?

Run `npx skills add BiFangKNT/mtga --skill ast-grep -a claude-code`. Or copy the skill folder (.codex/skills/ast-grep in BiFangKNT/mtga) into .claude/skills/ast-grep in your project. Claude Code loads it when a task matches its description.

How do I install Ast Grep in Codex?

Run `npx skills add BiFangKNT/mtga --skill ast-grep -a codex`. Or copy the skill folder (.codex/skills/ast-grep in BiFangKNT/mtga) into .agents/skills/ast-grep in your project. Codex loads it when a task matches its description.

Can I use Ast Grep in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add BiFangKNT/mtga --skill ast-grep -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/ast-grep, .gemini/skills/ast-grep, .github/skills/ast-grep and .opencode/skills/ast-grep in your project.

What does Ast Grep need to run?

SKILL.md names no scripts, command-line tools or credentials: Ast Grep is instructions for the agent only.

Does Ast Grep access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Ast Grep safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Ast Grep use?

Ast Grep is published under the AGPL-3.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Ast Grep use?

About 802 tokens (SKILL.md is roughly 3.2k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 2.9k tokens, read only when the agent opens those files.

What are the alternatives to Ast Grep?

Skills that share tags, products or a category with Ast Grep: Lsp Code Analysis (lsp-client/lsp-skill, 118 stars), Gograph Go Repository Intelligence (ozgurcd/gograph, 228 stars), Ripwire Graph Query (redhat-et/ripwire, 2.4k stars) and CodeNavi (tech-leads-club/agent-skills, 7k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Ast Grep?

BiFangKNT (a GitHub user) maintains it in BiFangKNT/mtga, which has 1,169 GitHub stars. The repository holds 6 skills in this directory. The repository was last updated on June 18, 2026.

Source: BiFangKNT/mtga on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Ast Grep

Facts

At a glance

What it does

When your agent uses it

Example prompts

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

ast-grep Code Search

Overview

General Workflow

Step 1: Understand the Query

Step 2: Start with the Smallest Pattern

Step 3: Escalate to YAML Rule for Structure Logic

Step 4: Validate and Search

CLI Quick Reference

Inspect Code Structure (--debug-query)

Test Rules (scan with --stdin)

Search with Patterns (run)

Search with Rules (scan)

Tips for Writing Effective Rules

Default to stopBy: end for Deep Searches

Start Simple, Then Add Complexity

Metavariable Rules

No-Match Triage

Resources

references/

Files

Compare with similar skills

Similar skills

More from BiFangKNT/mtga

Related

Questions about Ast Grep