title: "Codebase Exploration Prompt Template" tested_with: claude-code: "1.0.x" codex-cli: "0.2.x" last_updated: 2026-03-21 status: proven difficulty: beginner prerequisites: []
Codebase Exploration Prompt Template
When to Use This Prompt
When you need to understand unfamiliar code, onboard to a new project, or map out a feature's implementation.
The Prompt
Explore this codebase and explain:
1. What the project does (one paragraph)
2. The key directories and what each contains
3. The main entry point(s) and how a request flows through the system
4. The 5 most important files and why they matter
# Adapt this by:
# - Narrow to a specific area: "Explore the authentication system"
# - Add specific questions: "How does the billing module calculate charges?"
# - Ask for a specific output format if needed
Why It Works
- Structured exploration: The numbered format prevents rambling summaries
- Progressive depth: Overview → structure → flow → specifics
- Actionable output: "The 5 most important files" gives you a reading list
Variations
Feature tracing:
Trace how [feature — e.g., "user login"] works from the UI to the database. Show the call chain with file names and function names.
Dependency mapping:
What external dependencies does [module/file] rely on? For each, explain what it's used for and whether there are alternatives.
Architecture decision investigation:
Why is [thing] implemented as [pattern]? Look at git history and code comments for context. Is this deliberate architecture or accumulated debt?
Example Output
Good output gives you a mental map you can navigate by. If the agent just lists every file, the scope was too broad — ask about a specific subsystem.