Frequently asked questions
What is the best agent harness if I want a turnkey coding agent today?
Top picks: opencode, Cline, Codex. See the “Coding agent products (IDEs, CLIs, full suites)” category for the full ranked list.
What is the best agent harness if I want an always-on personal agent that lives in my chat apps?
Top picks: OpenClaw, Hermes, Khoj. See the “Personal agent runtimes” category for the full ranked list.
What is the best agent harness if I want to extend Claude Code, Codex, or OpenCode with skills and slash commands?
Top picks: Anthropic Skills, wshobson/agents, superpowers. See the “Coding harness configs and SDKs” category for the full ranked list.
What is the best agent harness if I want to build my own coding harness from scratch?
Top picks: Claude Agent SDK, Google ADK, AutoHarness. See the “Coding harness configs and SDKs” category for the full ranked list.
What is the best agent harness if I want a drop-in memory layer for agents?
Top picks: Mem0, Graphiti (Zep), claude-mem. See the “Plugins, MCPs, CLI tools” category for the full ranked list.
What is the best agent harness if I want to plug hundreds to thousands of tools without context bloat?
Top picks: MCP-Zero, ToolGen, ToolRAG. See the “Progressive disclosure harnesses” category for the full ranked list.
What is the best agent harness if I want multi-agent orchestration?
Top picks: openai-agents-python, crewAI, autogen. See the “Multi-agent and orchestration” category for the full ranked list.
What is the best agent harness if I want a general LLM app framework?
Top picks: langgraph, langchain, llama-index. See the “Frameworks” category for the full ranked list.
What is the best agent harness if I want low-code / visual workflows?
Top picks: langflow, Flowise, Dify. See the “Frameworks” category for the full ranked list.
What is the best agent harness if I want browser-using agents?
Top picks: browser-use, Stagehand, WebVoyager. See the “Plugins, MCPs, CLI tools” category for the full ranked list.
What is the best agent harness if I want sandboxed code execution for agent-generated code?
Top picks: E2B, Agent Sandbox, Daytona. See the “Libraries and SDKs” category for the full ranked list.
What is the best agent harness if I want to evaluate or benchmark agents?
Top picks: SWE-bench, Terminal-Bench, AgencyBench. See the “Evaluation and benchmarking harnesses” category for the full ranked list.
What is the best agent harness if I want a deep research / autonomous research agent?
Top picks: deepagents, gpt-researcher, openagents. See the “Research and task-specific harnesses” category for the full ranked list.
What is the best agent harness if I want a provider-agnostic LLM pipe (not a framework)?
Top picks: LiteLLM, vercel/ai. See the “Libraries and SDKs” category for the full ranked list.
Which agent harnesses can run unattended (headless)?
Harnesses designed for unattended runs, batches, and fleets: opencode, OpenHands, goose, Symphony, Prime Agent, SWE-agent, Claude Agent SDK, RepoMaster.
Which agent harnesses survive a crash mid-task (durable)?
Harnesses whose execution state persists across restarts: langgraph-bigtool, QM, n8n, langgraph, mastra, letta, deepagents, pydantic-ai.
How many of these agent harnesses are open source?
124 of 167 carry a standard open-source license; the rest are source-available or unclear, and flagged per row.
What is an agent harness?
The runtime that turns a model into an agent: it decides what the model's reasoning is allowed to touch, and supplies the orchestration, tool wiring, memory, error recovery, and guardrails around per-turn inference.
Does the harness matter more than the model?
Often, yes, and measurably: the same weights scored about 30% on ARC-AGI-3 as a bare model and 95.5% inside the Prime Agent harness, and on SWE-bench Pro swapping only the harness moved GLM-5.2 from 23% to 52%. Harness rankings barely transfer across models (rank correlation about -0.05), so pick the harness and the model as a pair, and re-pick when the model changes.
Is Grok Bot an agent harness?
Yes, a managed one: xAI owns the loop, the tool wiring, the memory, and the approval rules, and every Bot on an account shares one cloud computer. It is not in the ranked list because the list ranks open repositories; the managed-vs-self-hosted guide compares it with Claude Managed Agents, QM, OpenClaw, Hermes, and OpenJarvis.
How is this list ranked?
By relevance to harness concerns (environment, orchestration, lifecycle, guardrails) and by GitHub stars (captured 2026-09-20); each project also carries an adoption-surface tier and autonomy/recovery scores.
How can an AI agent use this list directly?
Three machine-readable surfaces: harnesses.json (structured), llms.txt (one file), and an MCP server (uvx agent-harnesses-mcp) exposing recommend, compare, pick_harness, and search_harnesses.