Update Chat Generators to support mixed Tools and Toolsets

[vblagoje]

Background

In Haystack 2.19 we enhanced the tools parameter across all chat generators to accept Optional[Union[list[Union[Tool, Toolset]], Toolset]] (defined as ToolsType).

This enhancement allows users to:

• Pass a mixed list of Tool and Toolset objects
• Pass a single Toolset object directly
• Combine multiple toolsets with standalone tools in the same list

Previous limitation: Components required either a list of Tool objects OR a single Toolset, but not both in the same list.

New capability: Users can now organize tools into logical Toolsets while also including standalone Tool objects, providing greater flexibility. For example:

generator = OpenAIChatGenerator(
    tools=[math_toolset, weather_toolset, standalone_tool]
)

This change is fully backward compatible and preserves structure during serialization/deserialization.

Required Changes

All chat generators in haystack-core-integrations that support tools need to be updated to use the new ToolsType format. Based on the current inventory, the following integrations need updates:

Generators with Tool Support

• amazon-bedrock-haystack - AmazonBedrockChatGenerator
• anthropic-haystack - AnthropicChatGenerator
• cohere-haystack - CohereChatGenerator
• google-genai-haystack - Chat generators
• llama-cpp-haystack - LlamaCppChatGenerator
• llama-stack-haystack - Chat generators
• meta-llama-haystack - Chat generators
• mistral-haystack - MistralChatGenerator
• nvidia-haystack - Chat generators
• ollama-haystack - OllamaChatGenerator
• openrouter-haystack - Chat generators
• [ ] stackit-haystack - Chat generators tools not supported
• togetherai-haystack - Chat generators
• [ ] watsonx-haystack - Chat generators tools not supported

Reference Implementation

See the Haystack core implementations for complete examples:

• haystack/components/generators/chat/openai.py

Testing Considerations

Each integration should add tests to verify:

1. Accepting a list of Tool objects (existing behavior)
2. Accepting a single Toolset object (existing behavior)
3. Accepting a mixed list of Tool and Toolset objects (new capability)
4. Proper serialization/deserialization of all three formats
5. Detection of duplicate tool names across tools and toolsets

Acceptance Criteria

• All chat generators with tool support are updated to use ToolsType
• All affected integrations pass existing tests
• New tests added for mixed tools/toolsets functionality
• Documentation updated to reflect the new capability
• No breaking changes to existing APIs