Fix AssistantAgent Tool Call Behavior #2231

Job	Run time
lint	50s
mypy (./packages/autogen-core)	1m 56s
format	55s
mypy (./packages/autogen-magentic-one)	1m 7s
mypy (./packages/agbench)	57s
pyright (./packages/autogen-core)	56s
mypy (./packages/autogen-ext)	1m 38s
pyright (./packages/autogen-magentic-one)	1m 7s
mypy (./packages/autogen-agentchat)	1m 16s
pyright (./packages/agbench)	51s
pyright (./packages/autogen-ext)	1m 10s
pyright (./packages/autogen-agentchat)	1m 6s
check-proto-changes-python	1m 22s
docs (./packages/autogen-core)	1m 37s
docs-example-check (./packages/autogen-core)	2m 2s
test (./packages/autogen-core)	51s
test (./packages/autogen-magentic-one)	1m 28s
test (./packages/autogen-ext)	2m 6s
test (./packages/autogen-agentchat)	1m 5s
	24m 20s

Provide feedback