search-tools

# Search Tool Hierarchy

When searching code, use this decision tree:

## Decision Tree

```
Need CONCEPTUAL/SEMANTIC search?
  (how does X work, find patterns, understand architecture)
  → Use LEANN (/leann-search) - embedding-based semantic search
  → PreToolUse hook auto-redirects semantic Grep queries

Need to understand code STRUCTURE?
  (find function calls, class usages, refactor patterns)
  → Use AST-grep (/ast-grep-find)

Need to find TEXT in code?
  → Use Morph (/morph-search) - 20x faster
  → If no Morph API key: fall back to Grep tool

Simple one-off search?
  → Use built-in Grep tool directly
```

## Tool Comparison

| Tool | Best For | Requires |
|------|----------|----------|
| **LEANN** | Semantic search: "how does caching work", "error handling patterns", conceptual queries | Index built |
| **AST-grep** | Structural patterns: "find all calls to `foo()`", refactoring, find usages by type | MCP server |
| **Morph** | Fast text search: "find files mentioning error", grep across codebase | API key |
| **Grep** | Literal patterns, class/function names, regex | Nothing (built-in) |

## Examples

**LEANN** (semantic/conceptual):
- "how does authentication work"
- "find error handling patterns"
- "where is rate limiting implemented"

**AST-grep** (structural):
- "Find all functions that return a Promise"
- "Find all React components using useState"
- "Refactor all imports of X to Y"

**Morph** (text search):
- "Find all files mentioning 'authentication'"
- "Search for TODO comments"

**Grep** (literal):
- `class ProviderAdapter`
- `def __init__`
- Regex patterns

## LEANN Commands

```bash
# Search with semantic query
leann search opc-dev "how does blackboard communication work" --top-k 5

# List available indexes
leann list

# Rebuild index (when code changes)
leann build opc-dev --docs dir1 dir2 --no-recompute --no-compact --force
```