Awesome Harness Engineering

DeepSeek Harness: Everything is a Plugin.

Lightweight coding agent that runs in your terminal

Model Context Protocol Servers

Never stop coding. Free MIT AI gateway: one endpoint, 359 providers (150+ free), 1200+ models Kimi, Claude, GPT, Gemini, GLM, DeepSeek, MiniMax. Works with Claude Code, Codex, Cursor, OpenCode, Cline & Copilot. Quota-aware auto-fallback, RTK+Caveman compression saves 15-95% tokens, MCP/A2A, Desktop/PWA. Built by hundreds of contributors

Context7 Platform -- Up-to-date code documentation for LLMs and AI code editors

an open source, extensible AI agent that goes beyond code suggestions - install, execute, edit, and test with any LLM

Chrome DevTools for coding agents

Installable GitHub library of 1,800+ agentic skills for Claude Code, Cursor, Codex CLI, Gemini CLI, Antigravity, and more. Includes specialized plugins, installer CLI, bundles, workflows, and official/community skill collections.

Self-evolving Context Database for AI Agents. Unify Agent Memory, Knowledge RAG and Skills.

Teams-first Multi-agent orchestration for Claude Code

Playwright MCP server

🪢 Open source agent evals & observability: Trace, evaluate, and improve LLM applications with one open platform.

The AI Toolkit for TypeScript. From the creators of Next.js, the AI SDK is a free open-source library for building AI-powered applications and agents

Test your prompts, agents, and RAGs. Red teaming/pentesting/vulnerability scanning for AI. Compare performance of GPT, Claude, Gemini, DeepSeek, and more. Simple declarative configs with command line and CI/CD integration. Used by OpenAI and Anthropic.

Scale computer-use 2.0 with open-source drivers, cross-OS fleets, and benchmarks for training, evaluation, and data generation.

A collection of projects designed to help developers quickly get started with building deployable applications using the Claude API

OpenWiki is a CLI that writes and maintains agent documentation for your codebase.

AG-UI: the Agent-User Interaction Protocol. Bring Agents into Frontend Applications.

AI Observability & Evaluation

Practical patterns, starters & CLI tools for loop engineering with AI coding agents. Design systems that prompt and orchestrate agents (inspired by Addy Osmani and Boris Cherny). Includes loop-audit, loop-init, loop-cost.

Free, local tool to track AI coding token usage and cost across 37 tools and agents (Claude Code, Cursor, Codex, Gemini and more), by model, project, and task. npx codeburn

Visual testing tool for MCP servers

Build an agent harness and control it end-to-end. Open-source SDK for production AI agents in Python & TypeScript - any model, any cloud.

Self-hosted TypeScript agent runtime with durable approvals and verifiable run records. Own it, approve it, audit it.

🧊 Open source LLM observability platform. One line of code to monitor, evaluate, and experiment. YC W23 🍓

Zep | Examples, Integrations, & More

Amazon Bedrock Agentcore accelerates AI agents into production with the scale, reliability, and security, critical to real-world deployment.

Squad: AI agent teams for any project

A HTTP credential proxy and vault for AI agents like Claude Code, OpenClaw, Hermes, custom agents + harnesses, and more.

Open-source, end-to-end platform for evaluating, observing, and improving LLM and AI agent applications. Tracing · Evals · Simulations · Datasets · Gateway · Guardrails. Self-hostable. Apache 2.0.

a recursive self-improving harness designed to help your agents (and future iterations of those agents) succeed on any task

Weave is a toolkit for developing AI-powered applications, built by Weights & Biases.

A production-ready runtime framework for agent apps with secure tool sandboxing, Agent-as-a-Service APIs, scalable deployment, full-stack observability, and broad framework compatibility.

MCP Fusion - The TypeScript framework for secure MCP servers.

Build your own coding agent workshop - Feb 19th 2026

Open HTTP protocol for human decisions in AI agent workflows. Service-hosted reviews, structured approvals, selections and forms, with optional messenger actions.