FormInput generates a validated form from a Pydantic model. Define the model, add the provider, and the LLM can collect structured input from the user — no free-text parsing, no hallucinated responses.

from pydantic import BaseModel, Field
from fastmcp.apps.form import FormInput

class BugReport(BaseModel):
    title: str = Field(description="Brief summary")
    severity: Literal["low", "medium", "high", "critical"]
    description: str = Field(
        description="Detailed description",
        json_schema_extra={"ui": {"type": "textarea"}},
    )

mcp = FastMCP("My Server")
mcp.add_provider(FormInput(model=BugReport))

Field types, labels, placeholders, and validation are derived from the Pydantic model via Prefab's Form.from_model(). An optional on_submit callback processes the validated data server-side — without it, the validated JSON is returned directly.

Also bumps prefab-ui minimum to 0.15.0.