AI Agent Harnesses

**Point-in-time snapshot: April 2026**

Last updated: 06/04/2026

AI Agent Harnesses

Point-in-time snapshot: April 2026

A curated list of projects describing themselves as AI agent harnesses or related to "harness engineering."

A Note On Terminology

The term "agent harness" emerged in late 2025 / early 2026 as a way to describe the orchestration layer that runs an AI agent. A harness manages the tool-dispatch loop, permissions, context, and lifecycle of an agent — as distinct from a framework (which provides higher-level abstractions for building agents) or a backend (which provides the inference and model serving).

The term gained traction partly through the adjacent concept of "harness engineering" — the practice of configuring and optimizing these orchestration layers (writing CLAUDE.md files, designing tool schemas, structuring agent prompts, etc.).

This list captures projects that self-identify with the "harness" label as of April 2026. The terminology is still fluid and not universally agreed upon — some projects listed here blur the line between harness, framework, and agent platform.

Agent Harnesses

Projects that provide runtime orchestration for AI agents — tool dispatch, conversation loops, context management, and agent lifecycle.

Resource Lists & Guides

Projects focused on curating resources, guides, and best practices for harness engineering rather than providing a harness runtime.

Star counts as of April 2026. This is a static snapshot and will not be updated.