Set Anthropic max_tokens to 4096 by default (#1994)

Co-authored-by: Douwe Maan <hi@douwe.me>

Author: Kludex

pydantic_ai_slim/pydantic_ai/models/anthropic.py

@@ -28,7 +28,6 @@
     UserPromptPart,
 )
 from ..profiles import ModelProfileSpec
-from ..profiles.anthropic import AnthropicModelProfile
 from ..providers import Provider, infer_provider
 from ..settings import ModelSettings
 from ..tools import ToolDefinition
@@ -217,14 +216,11 @@ async def _messages_create(
 
         system_prompt, anthropic_messages = await self._map_message(messages)
 
-        max_tokens_limit = AnthropicModelProfile.from_profile(self.profile).anthropic_max_tokens_limit
-        max_tokens = min(model_settings.get('max_tokens', max_tokens_limit), max_tokens_limit)
-
         try:
             extra_headers = model_settings.get('extra_headers', {})
             extra_headers.setdefault('User-Agent', get_user_agent())
             return await self.client.beta.messages.create(
-                max_tokens=max_tokens,
+                max_tokens=model_settings.get('max_tokens', 4096),
                 system=system_prompt or NOT_GIVEN,
                 messages=anthropic_messages,
                 model=self._model_name,

pydantic_ai_slim/pydantic_ai/profiles/anthropic.py

@@ -1,40 +1,8 @@
 from __future__ import annotations as _annotations
 
-from dataclasses import dataclass
-
 from . import ModelProfile
 
 
-@dataclass
-class AnthropicModelProfile(ModelProfile):
-    """Profile for models used with AnthropicModel.
-
-    ALL FIELDS MUST BE `anthropic_` PREFIXED SO YOU CAN MERGE THEM WITH OTHER MODELS.
-    """
-
-    anthropic_max_tokens_limit: int = 1024
-    """The maximum number of tokens that can be generated by this model, as documented at https://docs.anthropic.com/en/docs/about-claude/models/overview. Defaults to 1024."""
-
-
-MAX_TOKENS = {
-    'claude-3-haiku': 4096,
-    'claude-3-opus': 4096,
-    'claude-3-5-haiku': 8192,
-    'claude-3-5-sonnet': 8192,
-    'claude-3-7-sonnet': 64000,
-    'claude-opus-4': 32000,
-    'claude-4-opus': 32000,
-    'claude-sonnet-4': 64000,
-    'claude-4-sonnet': 64000,
-}
-
-
 def anthropic_model_profile(model_name: str) -> ModelProfile | None:
     """Get the model profile for an Anthropic model."""
-    max_tokens = 1024
-    for model_prefix, model_max_tokens in MAX_TOKENS.items():
-        if model_name.startswith(model_prefix):
-            max_tokens = model_max_tokens
-            break
-
-    return AnthropicModelProfile(anthropic_max_tokens_limit=max_tokens)
+    return None