feat: MetaLlamaChatGenerator update tools param to ToolsType

[vblagoje]

Why:

Adopts Haystack's ToolsType to enable flexible tool composition, developers can now mix individual Tool objects and Toolset instances in a single list

part of:

• Update Chat Generators to support mixed Tools and Toolsets #2409

What:

• Updated tools parameter from Union[List[Tool], Toolset] to ToolsType in constructor and all methods
• Haystack dependency to 2.19.0 for ToolsType support
• Added tests for mixed tool collection initialization and request parameter formatting

How can it be used:

from haystack.tools import Tool, Toolset
from haystack_integrations.components.generators.meta_llama import MetaLlamaChatGenerator

weather_tool = Tool(name="weather", ...)
population_toolset = Toolset([...])

# NEW: Mix Tool and Toolset freely
generator = MetaLlamaChatGenerator(tools=[weather_tool, population_toolset])

How did you test it:

• Unit tests verify mixed tool initialization and correct API parameter formatting
• Backward compatibility validated for existing patterns (list of tools, single toolset)
• Added integration test test_live_run_with_mixed_tools() demonstrates end-to-end LLM tool invocation from mixed collections

Notes for the reviewer:

• MetaLlamaChatGenerator inherits from OpenAIChatGenerator, so tool handling is delegated to the parent class
• Fully backward compatible; no migration needed
• The integration test verifies that the Llama API correctly processes mixed tool collections

[sjrl]

Looks good! (other than failing tests)

PR moved back to draft

[vblagoje]

Looks good! (other than failing tests)

Yes, this one really requires attention to see what is going on now

[vblagoje]

@sjrl figured it out - weaker 17B model although Llama4 series can't handle multiple tool calls properly. Llama-3.3-70B-Instruct does it no problem!

[sjrl]

Nice, looks good!