Partial Success

# Partial Success

Report mixed success/failure results for batch operations.

## Category
Tool Output

## Context
Batch operations where some items may fail.

## Problem
All-or-nothing responses lose successful results when some fail.

## Solution
Report per-item status:
- **Successes**: Items that worked
- **Failures**: Items that failed with reasons
- **Summary**: Overall statistics
- **Retry guidance**: How to retry failures

## Example (Python)
```python
@tool
def send_invites(
    emails: list[str]
) -> InviteResult:
    """Send invites to multiple users.
    
    Returns success/failure for each email.
    """
    results = []
    for email in emails:
        try:
            invite_api.send(email)
            results.append(InviteStatus(email=email, success=True))
        except Exception as e:
            results.append(InviteStatus(email=email, success=False, error=str(e)))
    
    succeeded = [r for r in results if r.success]
    failed = [r for r in results if not r.success]
    
    return InviteResult(
        total=len(results),
        succeeded=len(succeeded),
        failed=len(failed),
        results=results,
        retry_hint=f"Retry with: send_invites([{', '.join(f.email for f in failed)}])" if failed else None
    )
```

## Considerations
- Always return partial successes, don't discard them
- Provide enough error detail to understand failures
- Include retry guidance for failed items

## Related Patterns
- batch-operation
- recovery-guide
- error-classification

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Source: https://arcade.dev/patterns/partial-success