⚠️ Warning
This model was fine-tuned for experimental purposes, as part of an investigation into reducing over-triggered tool calls (i.e., getting the model to correctly abstain when no tool is relevant).
nvidia/When2Call (train_sft) was included in training to improve this behavior. However, this had an unintended side effect: the model's core tool-calling ability degraded significantly. It now frequently asks the user for clarification/input even for simple, complete, unambiguous tool-call requests where all required parameters are already provided.
Do not use this model in production or for tool-calling tasks. It is kept public only as a record of this experiment (see BFCL eval results above — simple_python_acc and multiple_acc collapsed while irrelevance_acc hit ceiling, indicating over-correction rather than genuine improvement).
LoRA fine-tune of Qwen/Qwen2.5-3B-Instruct for function/tool calling.
Data
- Salesforce/xlam-function-calling-60k — 54,000 (tool-call)
- HuggingFaceH4/no_robots — 8,000, filtered ≤2,000 chars (no-tool SFT)
- nvidia/When2Call (train_sft) — 3,300 (irrelevance/negative signal)
- Concatenated, shuffled, formatted via
apply_chat_template
LoRA
r=32, lora_alpha=64, lora_dropout=0.05, target_modules=all-linear, bias=none, task_type=CAUSAL_LM
Training
lr=2e-4, epochs=1, per_device_batch=8, grad_accum=16 (effective 128), warmup_ratio=0.03, max_grad_norm=0.3, bf16=True, attn_implementation=sdpa, loss_type=nll
Training Results (step 505, final)
train_loss=0.354, val_loss=0.173, mean_token_accuracy=0.956, runtime≈4h02m (A100)
BFCL Eval Results (inspect_evals/bfcl)
Table with columns: Metric, Score| Metric | Score |
|---|
| accuracy (all) | 0.429 |
| irrelevance_acc | 1.000 |
| multiple_acc | 0.045 |
| parallel_acc | 0.595 |
| parallel_multiple_acc | 0.640 |
| simple_python_acc | 0.090 |
Note: irrelevance_acc reached 1.000 (perfect abstention), but simple_python_acc (0.090) and multiple_acc (0.045) collapsed even further. Even with a reduced When2Call subset (3.3k), the negative signal causes heavy over-abstention from tool calling.
Comparison to prior runs
Table with columns: Run, accuracy, irrelevance_acc, simple_python_acc, multiple_acc| Run | accuracy | irrelevance_acc | simple_python_acc | multiple_acc |
|---|
| Base Qwen2.5-3B | 0.815 | 0.608 | 0.953 | 0.910 |
| EN-only (xlam 60k) | 0.705 | 0.213 | 0.893 | 0.865 |
| EN + no_robots | 0.730 | 0.225 | 0.910 | 0.875 |