Why this model
MiniCPM5-1B-Agentic-Tooluse-v3 is fine-tuned specifically to parse a tool schema and a natural-language user request, then emit a structured, correctly-named, correctly-valued function call — the exact skill that powers LangChain agents, LlamaIndex pipelines, AutoGen, CrewAI, MCP tool servers, ReAct loops, and home-automation assistants.
Unlike most small open tool-calling models that stop at supervised fine-tuning, this model goes further with GRPO reinforcement learning on top of the SFT checkpoint, specifically rewarding the two hardest parts of tool calling: choosing the right function name and getting every argument value exactly right.
Compared to GPT-4o / Claude for function calling: this model is 100% free, runs locally, keeps all data private, has zero per-call cost, and is fine-tunable — it trades some absolute accuracy for massive gains in cost, latency, and privacy. The merged FP16 format means you can load it with a single AutoModelForCausalLM.from_pretrained() call, just like any base model.
Why this model
MiniCPM5-1B-Agentic-Tooluse-v3 is fine-tuned specifically for agentic tool/function calling: given a tool schema and a natural-language request, it reliably produces a correctly-named, correctly-structured, correctly-valued function call — the exact capability that powers LangChain/LlamaIndex/AutoGen/CrewAI agents, MCP tool servers, ReAct-style loops, and home-automation assistants.
This release combines QLoRA supervised fine-tuning with a GRPO reinforcement-learning refinement stage, specifically optimized to improve exact function-name selection and exact argument-value correctness — historically the two hardest failure modes for small (~1B) tool-calling models.
Results
Evaluated on a held-out 300-example test slice drawn from a seeded shuffle of ToolACE (see Split integrity).
The base-model column is the same model with the same prompt and no adapter.
The published weights are SFT + GRPO (see GRPO / RLVR). The SFT column is kept because every
negative result below is measured against it.
Table with columns: metric, v2 (previous release), SFT retrain (pre-GRPO), v3 = SFT + GRPO (published)| metric | v2 (previous release) | SFT retrain (pre-GRPO) | v3 = SFT + GRPO (published) |
|---|
parseable — output is a well-formed call | 0.9933 | 1.0000 | 1.0000 |
valid_name — name exists among the offered tools | 0.9700 | 0.9867 | 0.9867 |
expected_name — name matches gold | 0.9067 | 0.9567 |
GRPO buys +0.0100 on args_exact, the metric that matters here, and gives back 0.0034 (one test example
each) on expected_name and arg_key_overlap. That trade is reported rather than hidden: the mean moves
only +0.0006, so this is a targeted gain on the hardest metric, not a broad improvement.
Full 8-metric benchmark (held-out test set, n=300)
This table mirrors the evaluation format from v2 and shows Base, v2, and v3 side-by-side
across all 8 metrics using a single consistent harness and held-out test slice:
Table with columns: Metric, Base MiniCPM5-1B, v2 (previous release), v3 (this model), Delta (v2 → v3)| Metric | Base MiniCPM5-1B | v2 (previous release) | v3 (this model) | Delta (v2 → v3) |
|---|
| parseable_rate | 0.0133 | 0.9933 | 1.0000 | +0.0067 |
| valid_name_rate | 0.0133 | 0.9700 | 0.9867 | +0.0167 |
| expected_name_rate | 0.0133 | 0.9267 | 0.9533 | +0.0267 |
What the additional metrics mean:
no_schema_copy_rate — the model did not copy the tool schema's own field description
verbatim into an argument value.
no_repetition_rate — the completion did not contain a duplicated function-call block or
degenerate repeated-phrase loop. This model has a known weakness here: it often continues
generating filler content after the tool call completes. Use a parser that extracts the first
completed <function>...</function> block.
stopped_cleanly_rate — the model naturally stopped immediately after the completed
</function> tag with no trailing tokens. Use a parser that treats the first completed
<function>...</function> block as the action boundary — do not rely on natural end-of-generation.
Model details
-
Base model: openbmb/MiniCPM5-1B
-
Architecture: Llama-style causal language model, ~1.08B parameters
-
Format: merged full weights, safetensors, FP16 — no adapter/PEFT loading required
-
Training pipeline: QLoRA SFT on tool-calling trajectories → GRPO reinforcement learning targeting exact argument correctness
-
Compatible with: transformers, vLLM, SGLang, TGI, and any standard Hugging Face causal-LM serving pipeline
Quickstart
from transformers import AutoModelForCausalLM, AutoTokenizer
tok = AutoTokenizer.from_pretrained("ewinregirgojr/MiniCPM5-1B-Agentic-Tooluse-v3-Merged-FP16")
model = AutoModelForCausalLM.from_pretrained("ewinregirgojr/MiniCPM5-1B-Agentic-Tooluse-v3-Merged-FP16")
vLLM:
vllm serve ewinregirgojr/MiniCPM5-1B-Agentic-Tooluse-v3-Merged-FP16
Ideal use cases
-
Production agent backends that need a fast, cheap, self-hosted function-calling model
-
LangChain / LlamaIndex / AutoGen / CrewAI / MCP-based agents needing a small, reliable tool-calling backbone
-
On-device and edge deployments where a 7B+ model isn't an option
-
High-throughput services where per-request cost and latency matter more than squeezing out the last few points of accuracy from a much larger model
-
Teams that want a fully open-weight, fine-tunable starting point instead of depending on a closed API for structured tool calls
Base model architecture
MiniCPM5-1B uses a standard LlamaForCausalLM architecture:
Table with columns: Property, Value| Property | Value |
|---|
| Parameters (total) | 1,080,632,832 |
| Parameters (non-embedding) | 679,552,512 |
| Architecture | LlamaForCausalLM |
| Layers | 24 |
| Attention heads (GQA) | 16 Q / 2 KV |
| Context length | 131,072 tokens |
| Training | SFT → RL (GRPO) fine-tune on openbmb/MiniCPM5-1B |
Thinking mode
MiniCPM5-1B has a built-in <think>...</think> chat template. The same checkpoint can act as a fast assistant or a deliberate chain-of-thought reasoner — controlled by a single flag:
prompt = tokenizer.apply_chat_template(
messages, tools=tools, add_generation_prompt=True,
enable_thinking=False,
tokenize=False,
)
prompt = tokenizer.apply_chat_template(
messages, tools=tools, add_generation_prompt=True,
enable_thinking=True,
tokenize=False,
)
Important: always use enable_thinking=False for tool/function calling. With thinking ON the model spends its token budget inside <think>...</think> and may not reach a completed function call. All benchmark numbers in this card use thinking OFF.
Citation
If you use this model, please cite the base model paper:
@article{minicpm4,
title = {MiniCPM4: Ultra-Efficient LLMs on End Devices},
author = {MiniCPM Team},
journal = {arXiv preprint arXiv:2506.07900},
year = {2025}
}
And the ToolACE dataset used for fine-tuning:
@article{toolace,
title = {ToolACE: Winning the Points of LLM Function Calling},
author = {Liu, Ying and others},
journal = {arXiv preprint arXiv:2409.00920},
year = {2024}
}
ModelScope
The base model is also available on ModelScope (for users in China and East Asia):
(The fine-tuned adapter/GGUF builds are currently HuggingFace-only.)
v3 model family (this release)
Previous releases
FAQ
Do I need the adapter repo too? No — this repo already contains the fully merged weights. Use the adapter repo only if you want to load it on top of base MiniCPM5-1B yourself or continue fine-tuning.
What's the difference between this and the GGUF repo? This is full-precision FP16 safetensors for GPU-backed serving frameworks (transformers, vLLM, SGLang). The GGUF repo is quantized for CPU-friendly local inference via llama.cpp/Ollama/LM Studio.
How was v3 trained differently from v2? v3 continues from the v2-era recipe with an additional QLoRA SFT pass plus a GRPO reinforcement-learning stage explicitly rewarding exact argument-value correctness, which is what drives the args_exact improvement shown above.
Base model
Built on MiniCPM5-1B by OpenBMB.
Limitations