---
id: sigtools
version: "4.0.1"
license: MIT
license_treatment: permissive
maintenance: abandoned
---

# sigtools — Utilities for working with inspect.Signature objects.

License: permissive · Maintenance: abandoned · Downloads: 836.2K/mo

## What it is and what it does

Sigtools is a library for working with Python function signatures at runtime. It provides tools to resolve the true signature of a function even when decorators have wrapped or modified it, and utilities to define keyword-only parameters, annotations, and positional-only parameters in a way that can be introspected. The library also includes decorators for specifying how *args and **kwargs are handled, and function combination routines that preserve signature metadata.

The package is most useful for library authors and framework developers who need to preserve or manipulate callable signatures through layers of decoration, or who want to provide introspectable APIs with explicit parameter handling. It depends only on attrs and installs with low friction.

Use it for:

- Decorators that need to preserve the original function's signature so introspection tools see the correct parameters.
- Building frameworks where *args/**kwargs handling must be explicitly documented and introspectable by tools.
- Libraries that wrap functions and need to expose the wrapped function's true signature to callers.
- Code requiring keyword-only or positional-only parameter syntax with explicit introspection support.

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

Sigtools provides utilities to inspect and manipulate Python function signatures, including resolving signatures through decorators and creating introspectable wrappers that preserve signature information.

Yes, but with caution. The package is stable and permissively licensed, with low install friction and no known vulnerabilities. However, it is abandoned—no maintenance since October 2022. Install it if you need signature introspection and manipulation for existing code or stable use cases, but do not rely on it for active development or expect security updates. Consider forking or finding an actively maintained alternative if you need ongoing support.

## Install

pip install sigtools
uv add sigtools
poetry add sigtools

## Installing sigtools

Before you install: Low install friction with a single lightweight dependency (attrs). However, the package is abandoned—last release was in October 2022. No active maintenance or security updates should be expected.

License in practice: MIT license is permissive and imposes no significant restrictions on use, modification, or redistribution in most contexts.

Quickstart:

pip install sigtools

import sigtools

# Resolve a function's signature, accounting for decorators
sig = sigtools.signature(some_function)

Requires Python 3.6 or later.

Verify before relying:

- Whether the package's decorator and signature-manipulation features work correctly with Python versions beyond 3.9 despite abandonment.
- Whether existing code depending on sigtools continues to function in current production environments without maintenance patches.

## Package facts

- License: MIT (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: abandoned
- Downloads: 836.2K/month (top 5,000 on PyPI)
- Known vulnerabilities: none known

## Tags

function signature inspection, decorator signature preservation, python introspection utilities, callable signature manipulation, inspect.Signature utilities, introspection, decorators, abandoned

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