$ find your agent harness

A curated, verified, cross-vendor directory of AI agent harnesses — the runtime scaffolding that turns a model into an agent.

◆ 74 harnesses profiled · 9-axis capability schema · last verified 2026-07-08

2 of 74 harnesses · sorted by stars

Pi · Mario Zechner / Earendil (steward since Apr 2026)

★ 68,476 · high

Mario Zechner's radically minimal MIT/TypeScript harness (~68k stars): four tools (read/write/edit/bash), a ~300-word system prompt, deliberately no built-in MCP/subagents/permission-popups, with everything else added via TypeScript extensions, skills, and npm/git-shareable packages across interactive, print/JSON, RPC, and SDK modes.

OSS coding harnessesopen-sourcebyok✓ skills✓ local models

Goose · Block → Agentic AI Foundation (Linux Foundation)

★ 50,812 · high

Block's Rust-built, Apache-2.0 general engineering agent — now stewarded by the Linux Foundation's Agentic AI Foundation — distinguished by the deepest MCP integration in the ecosystem (70+ extensions, can also act as an MCP server) and shareable YAML 'Recipes' that scaled agent workflows to 60% of Block.

OSS coding harnessesopen-sourcebyok✓ mcp✓ skills✓ local models