Flexible handling of dspy.ToolCalls parsing

[chenmoneygithub]

We have observed that LMs can mess up the deeply nested type, especially when it understands the semantics behind the scene, specifically dspy.ToolCalls here. We are expecting the format {"tool_calls": [{"name": "foo", "args": {...}}, {"name": "bar", "args": {...}}]}, but in reality there are a few cases seen from the same LM:

• {"name": foo, "args": {...}}, which is just a dict of information of one function calling. This behavior is pretty common, it exists not just in those small models on ollama, but also gpt-4o-mini, gpt-4o, even gemini-2.5.
• [{"name": "foo", "args": {...}}, {"name": "bar", "args": {...}}]. The outer tool_calls key is lost.

Since this is a stable pattern, it makes sense to have the default type handle this parsing.