MCP-CustomTool: Unit Tests

[souvikghosh04]

Goal: Add comprehensive unit tests for existing implementation

Files to Create:

src/Azure.DataApiBuilder.Mcp.Tests/DynamicCustomToolTests.cs

Tool metadata generation (name normalization, description)
Parameter schema building (type mapping, descriptions, required fields)
Input validation (constructor validation for non-SP entities)
Edge cases (null descriptions, empty parameters, special characters in names)
src/Azure.DataApiBuilder.Mcp.Tests/CustomMcpToolFactoryTests.cs

Tool filtering (SP + CustomToolEnabled = true)
Tool creation count validation
Skipping tables/views even with custom-tool enabled
Error handling for malformed entity configs
Logging verification
Test Coverage:

• Tool name conversion (GetUserProfile → get_user_profile)
• Parameter schema generation from ParameterMetadata
• Description propagation (entity + parameters)
• Fail-fast for non-stored-procedure entities
• Factory filtering logic

Deliverable: Test coverage for infrastructure without integration concerns