[Core] Feat Pretty Print Tool calls (#20997)

Right now, `tool_calls` are not included in the `pretty_print()` output.
Would be nice to show!


![image](https://github.com/langchain-ai/langchain/assets/13333726/6a0ffca3-d02f-4e18-bc76-513eeca2e964)

libs/core/langchain_core/messages/ai.py

@@ -1,4 +1,4 @@
-from typing import Any, Dict, List, Literal
+from typing import Any, Dict, List, Literal, Union
 
 from langchain_core.messages.base import (
     BaseMessage,
@@ -69,6 +69,37 @@ class AIMessage(BaseMessage):
                 pass
         return values
 
+    def pretty_repr(self, html: bool = False) -> str:
+        """Return a pretty representation of the message."""
+        base = super().pretty_repr(html=html)
+        lines = []
+
+        def _format_tool_args(tc: Union[ToolCall, InvalidToolCall]) -> List[str]:
+            lines = [
+                f"  {tc.get('name', 'Tool')} ({tc.get('id')})",
+                f" Call ID: {tc.get('id')}",
+            ]
+            if tc.get("error"):
+                lines.append(f"  Error: {tc.get('error')}")
+            lines.append("  Args:")
+            args = tc.get("args")
+            if isinstance(args, str):
+                lines.append(f"    {args}")
+            elif isinstance(args, dict):
+                for arg, value in args.items():
+                    lines.append(f"    {arg}: {value}")
+            return lines
+
+        if self.tool_calls:
+            lines.append("Tool Calls:")
+            for tc in self.tool_calls:
+                lines.extend(_format_tool_args(tc))
+        if self.invalid_tool_calls:
+            lines.append("Invalid Tool Calls:")
+            for itc in self.invalid_tool_calls:
+                lines.extend(_format_tool_args(itc))
+        return (base.strip() + "\n" + "\n".join(lines)).strip()
+
 
 AIMessage.update_forward_refs()