[langchain]: Docs contradict on whether schema-only response_format=MyModel is allowed in LangChain ≥1.0

[ScarletMercy]

Type of issue

issue / bug

Language

Python

Description

Problem
The documentation gives two mutually exclusive statements about how to request structured output from an agent in LangChain ≥1.0.

Page: provider_strategy

As of langchain 1.0, simply passing a schema (e.g., response_format=ContactInfo) is no longer supported. You must explicitly use ToolStrategy or ProviderStrategy.

Page: response-format

Response Format
Controls how the agent returns structured data:

• ToolStrategy[StructuredResponseT]: Uses tool calling for structured output
• ProviderStrategy[StructuredResponseT]: Uses provider-native structured output
• type[StructuredResponseT]: Schema type - automatically selects best strategy based on model capabilities
• None: No structured output

When a schema type is provided directly, LangChain automatically chooses:

• ProviderStrategy for models supporting native structured output (e.g. OpenAI, Grok)
• ToolStrategy for all other models

The structured response is returned in the structured_response key of the agent’s final state.

Evidence (repro)
Running the following snippet today (2025-11-21) with langchain==1.0.8 (latest):

class Mood(BaseModel):
    mood: str = Field(..., description="LLM simulates mood from user message")
 

agent = create_agent(model, [], response_format=Mood)
resp = agent.invoke({"messages":  "Hello!"})
print(resp["messages"][-1])

Output contains a valid tool call and returns the expected structure:

content="Returning structured response: mood='friendly'" name='Mood' id=... tool_call_id='call_...'

No exception is raised, confirming that passing response_format=Mood (a schema type) is still accepted.

Suggested fix
Update the first page (provider_strategy) to align with the second page:

• Remove the claim that “passing a schema directly is no longer supported.”
• Clarify that supplying only a schema type is shorthand for “auto-select best strategy,” not deprecated.

Environment

langchain==1.0.8
Python 3.11.9