pokemon-go-mcp: Skill for Claude Code

Mypy - Professional Static Type Checking

Mypy is a static type checker for Python that finds bugs without running code. This skill provides comprehensive guidance for professional mypy integration and usage.

Quick Start

Installation and Basic Usage

# Install mypy
python3 -m pip install mypy

# Check a file
mypy program.py

# Check with strict mode
mypy --strict program.py

Basic Type Annotations

def greeting(name: str) -> str:
    return 'Hello ' + name

# Type checking catches errors
greeting(3)  # Error: Argument has incompatible type "int"; expected "str"

Configuration

Mypy supports multiple configuration formats (discovery order):

1. mypy.ini
2. .mypy.ini
3. pyproject.toml (with [tool.mypy] section)
4. setup.cfg (with [mypy] section)

Essential Configuration Options

# mypy.ini
[mypy]
python_version = 3.11
warn_return_any = True
warn_unused_configs = True
disallow_untyped_defs = True

# Per-module configuration
[mypy-module_name.*]
ignore_missing_imports = True

See references/config_file.md for complete configuration reference.

Core Workflows

Adding Types to Existing Code

1. Start with --check-untyped-defs for gradual typing
2. Use # type: ignore comments sparingly for temporary exceptions
3. Add type annotations incrementally, module by module
4. Enable stricter checks progressively

See references/existing_code.md for migration strategies.

Resolving Type Errors

When mypy reports errors:

1. Check the error code (e.g., [attr-defined])
2. Consult error code documentation:
   • references/error_code_list.md - Default errors
   • references/error_code_list2.md - Optional checks
3. Use type narrowing techniques when needed
4. Consider reveal_type() for debugging type inference

See references/common_issues.md for troubleshooting.

Working with Advanced Types

Generics: references/generics.md

• TypeVar, Generic classes, bounded type variables
• Variance (covariant, contravariant, invariant)