majiayu000 MCP Tool Selection Rules
Core principle: MCP Qdrant-Indexer tools are primary for exploring code and history. Start with MCP for exploration, debugging, or "where/why" questions; use literal search/file-open only for narrow exact-literal lookups.
Use MCP Qdrant-Indexer When
- Exploring or don't know exact strings/symbols
- Need semantic or cross-file understanding (relationships, patterns, architecture)
- Want ranked results with surrounding context, not just line hits
- Asking conceptual/architectural or "where/why" behavior questions
- Need rich context/snippets around matches
Use Literal Search/File-Open Only When
- Know exact string/function/variable or error message
- Only need to confirm existence or file/line quickly (not to understand behavior)
Grep Anti-Patterns (DON'T)
grep -r "auth" . # → Use MCP: "authentication mechanisms"
grep -r "cache" . # → Use MCP: "caching strategies"
grep -r "error" . # → Use MCP: "error handling patterns"
grep -r "database" . # → Use MCP: "database operations"
Literal Search Patterns (DO)
grep -rn "UserAlreadyExists" . # Specific error class
grep -rn "def authenticate_user" . # Exact function name
grep -rn "REDIS_HOST" . # Exact environment variable
Quick Decision Heuristic
| Question Type | Tool |
|---|---|
| "Where is X implemented?" | MCP repo_search |
| "Who calls this and show code?" | MCP symbol_graph (hydrated w/ snippets) |
| "Callers of callers? Multi-hop?" | MCP neo4j_graph_query (transitive_callers, depth=2) |
| "What breaks if I change X?" | MCP neo4j_graph_query (impact, depth=2) |
| "Circular dependencies?" | MCP neo4j_graph_query (cycles) |
| "How does authentication work?" | MCP context_answer |
| "High-level module overview?" | MCP info_request (with explanations) |
| "Does REDIS_HOST exist?" | Literal grep |
| "Why did behavior change?" | search_commits_for + change_history_for_path |
If in doubt → start with MCP