A 0.8B personal assistant that beats models 2.5 times its size at tool use: meet BotPsy ๐Ÿ“ฑ

Most agent news is about giant models in giant data centers. That's why a post on the Hugging Face blog this morning caught my eye. Tether AI Research released BotPsy, a 0.8B-parameter model built for function calling and agentic workflows, small enough to run on a phone or a modest home server. The weights are already on the Hub under Apache 2.0, in bf16, Q8 and Q4, as safetensors and as GGUF files for llama.cpp.

What it can do

BotPsy is a fine-tuned Qwen3.5-0.8B, aimed at everyday assistant work: calendar, email, messaging, files, device settings, travel, shopping and simple web search. The interesting part is how far a sub-billion model gets on agent benchmarks. Compared with its base, BFCL v4 rises from 23.4 to 44.0, ACEBench from 30.1 to 58.7 and ฯ„-bench from 23.2 to 51.5. On five of six agentic benchmarks it also beats Qwen3.5-2B-Think, a model 2.5 times its size. Multi-turn work shows the biggest jump: BFCL v4 multi-turn goes from 7.5 to 46.1, and on ฯ„²-bench telecom, where the agent has to guide a user through troubleshooting over many turns, it scores 82.5.

My favourite number is a quiet one. On BFCL's hallucination tests, which check that the model declines when no suitable tool exists, BotPsy scores 86.1, the best of all models tested. For an agent that touches your inbox, knowing when not to act is half the job.

The training recipe

This is the part I'll be studying. Training happens in four stages, each starting from the best checkpoint of the previous one:

  1. Supervised fine-tuning on tool-use conversations, including cases where no tool should be called.
  2. Multi-teacher on-policy distillation. The student generates its own answers, and one of three specialist Qwen3.5-4B teachers (tool use, reasoning, instruction following) gives feedback on every token via reverse KL. This stage mainly recovers the knowledge and instruction following that SFT had damaged.
  3. Two rounds of RL with DAPO, using rule-based rewards that give partial credit for matching tool names, argument names and argument values.

The result is not just better tool use. IFEval climbs from 59.7 to 90.8, and the model reasons more efficiently: about 3 times fewer reasoning tokens per correct answer on GPQA Diamond, and runs that get stuck in reasoning loops on IFBench drop from 22.9% to 1.4%. On a small device, shorter reasoning means faster answers and less battery.

Honest limits

The team is refreshingly clear about weak spots. Deep research stays hard (BrowseComp-Plus is only 4.5), knowledge still scales with size, and instruction following fades as instructions pile up over turns. It was trained mainly in English, and Hindi and Russian lag far behind. They say plainly that it makes mistakes and shouldn't be used for high-stakes decisions involving money, health or sensitive personal data. I appreciate that tone a lot.

Why this makes me happy

For me this is the direction that matters: private, cheap agents that live on your own hardware and don't break when a cloud provider changes its terms. A 0.8B model that knows when to call a tool, and when to step back, is exactly the kind of building block I'd love to try in a homelab setup or a small learning assistant. Download it, run it in llama.cpp, and see what a tiny agent can do. ๐Ÿ™‚

Sources

Reacties

Populaire posts van deze blog

Meta just shared the full recipe for a 30B agent model you can run at home ๐Ÿง 

SpaceX just asked to fly Starship hundreds of times a year ๐Ÿš€

AI that can actually "see" a crystal ๐Ÿ”ฌ