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Your First Tasks

Let’s walk through common tasks you’ll do with Claude Code. These examples use Python, but the patterns apply to any language.

Task 1: Understand Unfamiliar Code

Section titled “Task 1: Understand Unfamiliar Code”

You’ve just joined a project. Start here:

> explain this codebase at a high level


> what are the main entry points?


> draw a diagram of how the components interact

Deep Dive on Specific Code

Section titled “Deep Dive on Specific Code”
> walk me through what happens when a user logs in


> explain the User model and its relationships


> what's the purpose of the middleware in app.py?

Task 2: Fix a Bug

Section titled “Task 2: Fix a Bug”

The best bug fix prompts include context:

Good:

> users report that password reset emails aren't being sent.
> the error in the logs is "SMTP connection refused"
> find and fix the issue

Even Better:

> users report that password reset emails aren't being sent
> this started happening after yesterday's deployment
> the error in the logs is "SMTP connection refused"
> we use SendGrid for email
> find and fix the issue

Let Claude Investigate

Section titled “Let Claude Investigate”
> the checkout flow is broken but I don't know why
> run the tests and help me figure out what's wrong

Claude will:

  1. Run your test suite
  2. Analyze failures
  3. Trace the issue to source
  4. Propose a fix

Task 3: Write Tests

Section titled “Task 3: Write Tests”
> write pytest unit tests for the UserService class
> focus on edge cases and error conditions

Test Example Session

Section titled “Test Example Session”
claude > write tests for the payment processing module


I'll create comprehensive tests for payments.py. Here's my plan:


1. Test successful payment processing
2. Test insufficient funds handling
3. Test invalid card data
4. Test network timeout recovery
5. Test idempotency (duplicate requests)


Creating tests/test_payments.py...


claude > run them


Running: pytest tests/test_payments.py -v


test_successful_payment PASSED
test_insufficient_funds PASSED
test_invalid_card PASSED
test_network_timeout PASSED
test_idempotency FAILED  # Oops, found a bug!


The idempotency test failed. Looking at the code, I see that
duplicate requests aren't being handled. Want me to fix this?

Task 4: Refactor Code

Section titled “Task 4: Refactor Code”

Tell Claude what you want to achieve:

> refactor the database module to use connection pooling


> this function is 200 lines long, break it into smaller functions


> convert this class to use async/await


> extract the validation logic into a separate module

Refactor with Constraints

Section titled “Refactor with Constraints”
> refactor the auth module
> constraints:
> - don't change the public API
> - keep backward compatibility
> - add type hints

Task 5: Add a Feature

Section titled “Task 5: Add a Feature”

For larger features, use plan mode (press Alt+M to cycle to plan mode):

> add a user notification system


Claude will ask:
- What types of notifications? (email, push, in-app)
- What events trigger notifications?
- Should users be able to configure preferences?
- What's the delivery mechanism?

Feature Implementation Flow

Section titled “Feature Implementation Flow”
claude > add rate limiting to the API


Let me understand the requirements:


1. What endpoints need rate limiting?
   ○ All endpoints
   ○ Only authenticated endpoints
   ○ Specific endpoints (list them)


[You select: Only authenticated endpoints]


2. What rate limit strategy?
   ○ Fixed window (e.g., 100 requests per minute)
   ○ Sliding window
   ○ Token bucket


[You select: Fixed window]


3. Where should limits be stored?
   ○ In-memory (resets on restart)
   ○ Redis (persistent across instances)


[You select: Redis]


Great, here's the plan:


1. Add redis-py to requirements.txt
2. Create rate_limiter.py with RateLimiter class
3. Add rate_limit decorator
4. Apply to authenticated routes
5. Add tests
6. Update API documentation


Proceed with implementation?

Task 6: Review Code

Section titled “Task 6: Review Code”
> review my changes before I commit


> are there any security issues in the auth module?


> check for performance problems in the database queries


> is this code following our style guide?

Task 7: Documentation

Section titled “Task 7: Documentation”
> add docstrings to all public functions in api.py


> create a README for this project


> generate API documentation from the route handlers


> write a developer setup guide

Pro Tips

Section titled “Pro Tips”

Be Specific About Constraints

Section titled “Be Specific About Constraints”
> add caching to the user lookup
> use Redis, not in-memory
> cache for 5 minutes
> invalidate on user update

Provide Examples

Section titled “Provide Examples”
> create a new API endpoint similar to /api/users
> but for products
> use the same patterns and error handling

Reference Existing Code

Section titled “Reference Existing Code”
> add a new model like the User model in models.py
> for storing product reviews

Iterate

Section titled “Iterate”

Don’t try to do everything in one prompt:

# First, get the basic structure
> create a new endpoint for product search


# Then refine
> add pagination to the search results


# Then optimize
> add caching for common searches