Which agent harness do you use and why?

I see a new one being launched every few days... How do these new harnesses compare to claude code, pi etc. has anyone switched from these?

which harness to prefer and why

edit:Ive tried several different ones claude code, deepagents(langgraph), opencode, pi, and trueforge

my thoughts-

claude code - strongest on maturity and the managed experience but cost and token burn is high

deepagents - interesting middle ground if you want a more structured agent framework and the flexibility of an open-source stack. im interested in testing it more extensively on longer-running workloads fs

trueforge - this is a recent one, this was interesting to me because of its runtime-efficiency, also it allows separate the model from the runtime, which makes experimenting with different models much easier https://github.com/truefoundry/trueforge

why?? - i also ran a benchmark on a real agent workload same model, same prompt, same tasks to compare these

adding the results of benchmarking i ran to compare this so I tried to do this by running 14 cross-system tasks, three mcp servers behind them - a crm, an issue tracker, and a doc store through claude's managed agents, langchain's deepagents and trueforge, both open-source agent harnesses

the result that was most surprising:

Claude Managed Agents + Opus 4.8: 11/14 tasks solved | $11.8/run | 10.0M tokens/run

TrueForge + Opus 4.8: 11/14 tasks solved | $8.6/run | 3.7M tokens/run

Same model. Same benchmark. Same average solve rate, to my surprise trueforge used about 63% fewer tokens and cost about 30% less per run.

similar difference in tool usage: trueforge averaged 19 tool calls per task vs 32 for Claude Managed Agents.

Then I tried changing the model.

trueforge + GLM-5.2: 11.7/14 solved | $3.0/run | 3.8M tokens/run

On this benchmark, that was a slightly higher average solve rate than Claude Managed Agents + Opus at roughly 75% lower cost.

The token savings alone make this sooo interesting especially because the solve rate stays comparable so this one was worth checking out ig

but this is still v early and the OSS runtime does not yet have first-class tracing/eval tooling. They don't ship their own code-execution sandbox, so you need to plug one in and context compaction is intentionally lossy.

So it is definitely not a replacement for a mature managed agent platform or other harnesses in the comparison, feature-for-feature today btu what I do find interesting is that the core runtime can already be competitive on these tasks while staying open, model-neutral, and deployable on my own infrastructure this was their benchmark kit i used https://github.com/truefoundry/trueforge/tree/main/benchmark