Built-in tools

• Grep searches file contents for patterns such as function names, error messages, or imports.
• Glob matches file paths by name or extension pattern (for example **/*.test.tsx).
• Read and Write operate on full files; Edit makes targeted changes using unique text matching.
• When Edit fails because the anchor is not unique, fall back to Read plus Write.
• Codebase understanding is built incrementally: Grep for entry points, then Read to follow imports.

• Choose Grep to find callers or error sources, and Glob to find files by naming pattern.
• Use Read followed by Write when Edit cannot find a unique anchor.
• Explore from entry points rather than reading every file up front.
• Trace usage through wrapper modules by listing exported names first, then searching for each.

• "Glob can search inside files." It matches paths only.
• "Edit will eventually work if retried." The same non-unique text fails the same way.
• "Reading the whole repository first gives the best answers." It exhausts context and buries the relevant parts.

Reading every file before answering, and single-name searches that miss functions re-exported under aliases.

• 5.4Context in large codebases
• 3.4Plan mode vs direct execution
• 2.4MCP servers in Claude Code and agents