| name | osgrep |
| description | Semantic code search using natural language queries. Use when users ask "where is X implemented", "how does Y work", "find the logic for Z", or need to locate code by concept rather than exact text. Returns file paths with line numbers and code snippets. |
| allowed-tools | Bash(osgrep:*), Read |
| license | Apache-2.0 |
When to Use
Use this to find code by concept or behavior (e.g., "where is auth validated", "how are plugins loaded").
Note: This tool prioritizes finding the right files and locations in the code. Snippets are truncated (max 16 lines) and are often just previews.
Example:
osgrep "how are plugins loaded"
osgrep "how are plugins loaded" packages/transformers.js/src
Strategy for Different Query Types
For Architectural/System-Level Questions (auth, LSP integration, file watching)
- Search Broadly First: Use a conceptual query to map the landscape.
osgrep "authentication authorization checks"
- Survey the Results: Look for patterns across multiple files:
- Are checks in middleware? Decorators? Multiple services?
- Do file paths suggest different layers (gateway, handlers, utils)?
- Read Strategically: Pick 2-4 files that represent different aspects:
- Read the main entry point
- Read representative middleware/util files
- Follow imports if architecture is unclear
- Refine with Specific Searches: If one aspect is unclear:
osgrep "session validation logic"osgrep "API authentication middleware"
For Targeted Implementation Details (specific function, algorithm)
- Search Specifically: Ask about the precise logic.
osgrep "logic for merging user and default configuration"
- Evaluate the Semantic Match:
- Does the snippet look relevant?
- Crucial: If it ends in
... or cuts off mid-logic, read the file.
- One Search, One Read: Use osgrep to pinpoint the best file, then read it fully.
Output Format
Returns: path/to/file:line [Tags] Code Snippet
[Definition]: Semantic search detected a class/function here. High relevance....: Truncation Marker. Snippet is incomplete—use read_file for full context.
Tips
- Trust the Semantics: You don't need exact names.
osgrep "how does the server start" works better than guessing osgrep "server.init".
- Watch for Distributed Patterns: If results span 5+ files in different directories, the feature is likely architectural—survey before diving deep.
- Scope When Possible: Use path constraints to focus:
osgrep "auth" src/server/
- Don't Over-Rely on Snippets: For architectural questions, snippets are signposts, not answers. Read the key files.
- "Still Indexing...": If you see this, please stop, alert the user that the index is ongoing and ask them if they wish to proceed. Results will be partial until the index is complete.
