Panther MCP Server

# Code Guidelines - Always use and commit changes in feature branches containing the human's git user - Use the @Makefile commands for local linting, formatting, and testing - Always update the __init__.py when adding new files for prompts, resources, or tools - Always update the @README.md when adding or updating tool names, changing supported installations, and any user-facing information that's important. For developer-oriented instructions, update @src/README.md ## Development Documentation For comprehensive development guidance, refer to: - __[@docs/mcp-development-best-practices.md](docs/mcp-development-best-practices.md)__ - Core principles, parameter patterns, error handling, security practices - __[@docs/mcp-testing-guide.md](docs/mcp-testing-guide.md)__ - Testing strategies and patterns - __[@docs/tool-design-patterns.md](docs/tool-design-patterns.md)__ - Tool design patterns and anti-patterns - __[@docs/server-architecture-guide.md](docs/server-architecture-guide.md)__ - Server architecture and context management ## Validation Guidelines ### What FastMCP/Pydantic Handles Automatically - **Basic type validation**: `str`, `int`, `list[str]`, etc. are validated automatically - **Field constraints**: `ge`, `le`, `min_length`, `max_length` work perfectly - **List type validation**: `list[str]` automatically validates that all items are strings - **Optional types**: `str | None` works correctly ### When to Use BeforeValidator Only use `BeforeValidator` for: - **Custom domain validation** - validating specific enum values (e.g., `["OPEN", "TRIAGED", "RESOLVED", "CLOSED"]`) - **Complex validation logic** - date format parsing, custom business rules - **Value transformation** - converting or normalizing input values - **Cross-field validation** - validating combinations of parameters ### When NOT to Use BeforeValidator Avoid `BeforeValidator` for basic validation that Field constraints can handle: - ❌ `_validate_positive_integer` → ✅ Use `Field(ge=1)` - ❌ `_validate_non_empty_string` → ✅ Use `Field(min_length=1)` - ❌ `_validate_string_list` → ✅ Use `list[str]` type hint ## Quick Reference: Annotated Tool Fields Always use the `Annotated[Type, Field()]` pattern for all tool parameters: ```python # Basic validation with Field constraints (preferred) positive_int: Annotated[ int, Field(ge=1, description="Must be positive integer"), ] = 1 # Complex validation requiring BeforeValidator status: Annotated[ str, BeforeValidator(_validate_alert_status), Field( description="Alert status", examples=["OPEN", "TRIAGED", "RESOLVED", "CLOSED"] ), ] ``` See [@docs/mcp-development-best-practices.md](docs/mcp-development-best-practices.md#parameter-patterns) for complete parameter type patterns and guidelines.