feat: protect against anthropic nested tool args (#2250)

letta/agents/letta_agent.py

@@ -488,8 +488,11 @@ class LettaAgent(BaseAgent):
 
         try:
             tool_args = json.loads(tool_call_args_str)
+            assert isinstance(tool_args, dict), "tool_args must be a dict"
         except json.JSONDecodeError:
             tool_args = {}
+        except AssertionError:
+            tool_args = json.loads(tool_args)
 
         # Get request heartbeats and coerce to bool
         request_heartbeat = tool_args.pop("request_heartbeat", False)

letta/interfaces/anthropic_streaming_interface.py

@@ -1,3 +1,4 @@
+import json
 from datetime import datetime, timezone
 from enum import Enum
 from typing import AsyncGenerator, List, Union
@@ -89,7 +90,13 @@ class AnthropicStreamingInterface:
 
     def get_tool_call_object(self) -> ToolCall:
         """Useful for agent loop"""
-        return ToolCall(id=self.tool_call_id, function=FunctionCall(arguments=self.accumulated_tool_call_args, name=self.tool_call_name))
+        # hack for tool rules
+        tool_input = json.loads(self.accumulated_tool_call_args)
+        if "id" in tool_input and tool_input["id"].startswith("toolu_") and "function" in tool_input:
+            arguments = str(json.dumps(tool_input["function"]["arguments"], indent=2))
+        else:
+            arguments = self.accumulated_tool_call_args
+        return ToolCall(id=self.tool_call_id, function=FunctionCall(arguments=arguments, name=self.tool_call_name))
 
     def _check_inner_thoughts_complete(self, combined_args: str) -> bool:
         """

letta/llm_api/anthropic_client.py

@@ -369,11 +369,11 @@ class AnthropicClient(LLMClientBase):
                     content = strip_xml_tags(string=content_part.text, tag="thinking")
                 if content_part.type == "tool_use":
                     # hack for tool rules
-                    input = json.loads(json.dumps(content_part.input))
-                    if "id" in input and input["id"].startswith("toolu_") and "function" in input:
-                        arguments = str(input["function"]["arguments"])
+                    tool_input = json.loads(json.dumps(content_part.input))
+                    if "id" in tool_input and tool_input["id"].startswith("toolu_") and "function" in tool_input:
+                        arguments = str(tool_input["function"]["arguments"])
                     else:
-                        arguments = json.dumps(content_part.input, indent=2)
+                        arguments = json.dumps(tool_input, indent=2)
                     tool_calls = [
                         ToolCall(
                             id=content_part.id,