From 23eb0877596fd54d00576d7c13e1b59cfde13070 Mon Sep 17 00:00:00 2001
From: Kevin Lin <klin5061@gmail.com>
Date: Mon, 25 Aug 2025 13:36:55 -0700
Subject: [PATCH] fix: pass thinking to anthropic client  (#4150)

---
 letta/llm_api/anthropic_client.py | 24 +++++++++++++++++++-----
 letta/schemas/message.py          |  2 +-
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/letta/llm_api/anthropic_client.py b/letta/llm_api/anthropic_client.py
index b2e90889..ef54ff62 100644
--- a/letta/llm_api/anthropic_client.py
+++ b/letta/llm_api/anthropic_client.py
@@ -287,12 +287,26 @@ class AnthropicClient(LLMClientBase):
         else:
             anthropic_tools = None
 
+        thinking_enabled = False
+        if messages:
+            for message in messages:
+                if isinstance(message.get("content"), list):
+                    for content_block in message["content"]:
+                        if content_block.get("type") == "thinking":
+                            thinking_enabled = True
+                            break
+
         try:
-            result = await client.beta.messages.count_tokens(
-                model=model or "claude-3-7-sonnet-20250219",
-                messages=messages or [{"role": "user", "content": "hi"}],
-                tools=anthropic_tools or [],
-            )
+            count_params = {
+                "model": model or "claude-3-7-sonnet-20250219",
+                "messages": messages or [{"role": "user", "content": "hi"}],
+                "tools": anthropic_tools or [],
+            }
+
+            if thinking_enabled:
+                count_params["thinking"] = {"type": "enabled", "budget_tokens": 16000}
+
+            result = await client.beta.messages.count_tokens(**count_params)
         except:
             raise
 
diff --git a/letta/schemas/message.py b/letta/schemas/message.py
index 4fd0a8ea..5376cd5f 100644
--- a/letta/schemas/message.py
+++ b/letta/schemas/message.py
@@ -846,7 +846,7 @@ class Message(BaseMessage):
             }
             content = []
             # COT / reasoning / thinking
-            if self.content is not None and len(self.content) > 1:
+            if self.content is not None and len(self.content) >= 1:
                 for content_part in self.content:
                     if isinstance(content_part, ReasoningContent):
                         content.append(