ast-grep

name	ast-grep
description	Structural code search and rewrite via the bundled ast_grep MCP server. Use for AST patterns ($VAR, $$$), not regex. Prefer over Grep when matching syntax trees.
user_invocable	false

AST-Grep (MCP ast_grep)

Bundled server: node ${GROK_PLUGIN_ROOT}/vendor/ast-grep-mcp/dist/cli.js mcp

When to use

• Find or rewrite syntax-shaped code (functions, imports, classes, control flow)
• Refactors that must respect language grammar (25 languages)

When not to use

• Plain text, alternation (foo|bar), or regex wildcards → use Grep / rg instead

Tools (via CallMcpTool, server ast_grep)

Tool	Purpose
search	AST pattern search (pattern, lang, optional paths, globs, context)
replace	AST rewrite (pattern, rewrite, lang; dryRun defaults to true)

Pattern syntax

• $VAR — one AST node (identifier, expression, statement, …)
• $$$ — zero or more nodes (args, bodies, …)
• Patterns must be valid source for the chosen lang

Examples:

• TypeScript: function $NAME($$$) { $$$ }, console.log($$$)
• Python: def $FUNC($$$), class $C($$$) (no trailing colon in pattern)
• Go: func $NAME($$$) { $$$ }

Workflow

1. Search with a concrete pattern; narrow paths / globs if noisy.
2. Replace with dryRun: true first; review preview; then dryRun: false.
3. After edits, run LSP diagnostics on touched files (see skills/lsp).

Aliases

Some hosts expose the same tools as ast_grep_search / ast_grep_replace.