Fix self-service action creation when invocationMethod is provided as JSON string

[Copilot]

Problem

When using Claude via the MCP server to create self-service actions, the action creation was failing because the invocationMethod field was being passed as a JSON string instead of a proper JSON object. This caused Pydantic validation to fail since it expected one of the specific ActionInvocationMethod union types (WEBHOOK, GITHUB, GITLAB, etc.), not a string.

Example of the problematic input:

{
  "invocationMethod": "{\"type\": \"WEBHOOK\", \"url\": \"https://...\", \"method\": \"POST\"}"
}

Should be:

{
  "invocationMethod": {"type": "WEBHOOK", "url": "https://...", "method": "POST"}
}

Solution

Added field validation and model validation to the CreateActionToolSchema class that:

1. Field Validator: Detects when invocation_method is provided as a JSON string and parses it into a dictionary
2. Model Validator: Handles the invocationMethod alias and parses JSON strings at the model level
3. Comprehensive Coverage: Works with all invocation method types (WEBHOOK, GITHUB, GITLAB, AZURE-DEVOPS, KAFKA)
4. Backward Compatibility: Maintains support for existing object-based invocation methods
5. Error Handling: Provides clear error messages for invalid JSON strings

Changes

• Enhanced CreateActionToolSchema with @field_validator and @model_validator decorators
• Added JSON string parsing logic that gracefully handles both string and object inputs
• Added comprehensive test cases covering both WEBHOOK and GITHUB invocation method types
• Ensured the fix works for both invocationMethod and invocation_method field names

Testing

Added test cases that verify:

• ✅ String JSON invocation method parsing for WEBHOOK type
• ✅ String JSON invocation method parsing for GITHUB type
• ✅ Normal object invocation methods continue to work
• ✅ Invalid JSON strings produce clear error messages

The fix is minimal and surgical - it only adds the necessary validation to handle the specific Claude integration issue without affecting any other functionality.

Fixes #52.

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[Matanga1-2]

It works better now, as the input generated by Claude is transformed to a correct one in Port.

Please

1. Consider if there is also a required change to prevent the AI from generating the bad input to start with (maybe in the tool description? properties?)
2. Upsert the version in pyproject.toml and add a new changelog entry

[Copilot]

It works better now, as the input generated by Claude is transformed to a cor...

I've addressed both points:

1. Preventive improvements: Enhanced the tool description and field descriptions to guide AI models to provide the correct JSON object format from the start. Added clear examples and warnings in the tool description.

2. Version and changelog: Updated version to 0.2.19 in pyproject.toml (fixed duplicate entries) and added a comprehensive changelog entry documenting the fix.

Changes are in commit 2b5fb4d.