Helptext generation¶

tyro.cli() automatically generates helptext for arguments from docstrings, comments, and annotations. This functionality relies heavily on docstring_parser.

Both callables (functions, objects with __call__ methods) and “struct” types (dataclasses.dataclass, NamedTuple, TypedDict, attrs, pydantic, etc) are inspected for helptext.

Helptext from docstrings¶

Note

✨ Docstrings are the recommended way to provide helptext for callables! ✨

General callables¶

For general callables, field helptext is extracted from the corresponding field docstring. Our examples use Google-style docstrings, but ReST, Numpydoc-style and Epydoc docstrings are supported as well:

def main(field1: str, field2: int = 3) -> None:
    """Helptext for the overall CLI interface.

    Args:
        field1: Helptext for field1.
        field2: Helptext for field2.
    """
    print(field1, field2)

Struct types¶

For fields defined using class attributes, enumerating arguments in class docstrings can be cumbersome. tyro.cli() also supports helptext from attribute docstrings:

@dataclasses.dataclass
class Args:
    field1: str
    """Helptext for field1."""
    field2: int = 3
    """Helptext for field2."""

Helptext from comments¶

For struct types, we also support helptext generation from comments. This can be turned off using tyro.conf.HelptextFromCommentsOff.

Inline comments¶

Inline comments can be more succinct than true attribute docstrings.

@dataclasses.dataclass
class Args:
    field1: str  # Helptext for field1.
    field2: int = 3  # Helptext for field2.

Preceding comments¶

These comments will apply to all fields that directly follow them. They can be handy for semantically grouping fields, such as the two string fields below.

@dataclasses.dataclass
class Args:
    # Strings. This will be displayed as helptext for both fields.
    field2.
    field1: str
    field2: str
    # An integer field.
    # Multi-line comments are supported.
    field3: int

Helptext from annotations¶

tyro.conf.arg()¶

tyro.conf.arg() includes a help argument that can be used to provide helptext for a field.

@dataclasses.dataclass
class Command:
    sources: Annotated[
        list[str],
        tyro.conf.arg(help="Filesystem locations or URLs."),
        # The 'help' argument will be become helptext for 'sources'
    ]

Doc objects¶

PEP 727 proposes a Doc object for specifying introspectable documentation.

Warning

As of this writing (2025-03-23), PEP 727 is in draft status. Please be advised that upstream support for this could disappear from typing_extensions.

from typing import Annotated
from typing_extensions import Doc
import dataclasses

@dataclasses.dataclass
class Config:
    input_file: Annotated[str, Doc("Path to the input file")]
    # The Doc string will become helptext for 'input-file'

Precedence rules¶

When multiple helptext sources are available, they are chosen in the following order of precedence:

tyro.conf.arg()
PEP 727 Doc
Docstrings
Comments