Saidzoda-Tajik-LFM-2.6B: Adapting a 2.6B Hybrid Model to Tajik Tool Calling, and What Continued Pretraining Takes Away
Organizations: Saidzoda AI Lab, Saidzoda Engineering Company, Dushanbe, Tajikistan
Abstract
We release Saidzoda-Tajik-LFM-2.6B, a Tajik adaptation of the 2.6B-parameter hybrid model LFM2.5-2.6B-Base, built for tool calling in Tajik on modest hardware. The recipe has two stages: LoRA continued pretraining (CPT) on 1,485,319 cleaned Tajik web documents for 3 epochs, then one epoch of supervised fine-tuning (SFT) on a mix of machine-translated Tajik tool calls, English tool calls kept as replay, and Tajik instructions. On a 174-item tool-calling test set built from BFCL v3 and machine-translated to Tajik, strict full-call accuracy on Tajik prompts rises from 20.69 for the base model to 64.14 (paired difference +43.45 points, 95% interval +35.2 to +51.7); a lenient parser that also accepts the base model's own call formats puts the base at 31.72. English shows no detectable change (76.55 and 77.24). Every CPT checkpoint scores zero: CPT removes the native tool-call format and, as the lenient re-scoring shows, part of the skill itself. Outside tool calling, accuracy on a Tajik knowledge benchmark rises from 28.0 to 35.0, Belebele Tajik shows no significant change, and English MMLU falls from 60.8 to 52.5. The model is not a general Tajik assistant. It almost never declines when no tool fits (6.9% correct on Tajik, against 31.0% for the base under the lenient parser), it is weak at multi-turn calls, and its calls should be checked before they are executed. We describe the data, the training settings and every evaluation in enough detail to repeat them.
Figures & tables
| Stage | English | Tajik |
|---|---|---|
| Base | 76.55 [69.7, 83.4] | 20.69 [14.5, 26.9] |
| CPT epoch 1 | 0.00 [0.0, 0.0] | 0.00 [0.0, 0.0] |
| CPT epoch 2 | 0.00 [0.0, 0.0] | 0.00 [0.0, 0.0] |
| SFT epoch 1 (released) | 77.24 [70.3, 84.1] | 64.14 [55.9, 71.7] |
| SFT epoch 2 | 76.55 [69.7, 83.4] | 63.45 [55.2, 71.0] |
| English | Tajik | |||
| Category | Base | SFT e1 | Base | SFT e1 |
| Single ( ) | 95.51 [91.0, 98.9] | 94.38 [88.8, 98.9] | 30.34 [21.3, 40.4] | 77.53 [68.5, 85.4] |
| Parallel ( ) | 70.37 [51.9, 85.2] | 74.07 [55.6, 88.9] | 7.41 [0.0, 18.5] | 70.37 [51.9, 85.2] |
| Multi-turn ( ) | 24.14 [10.3, 41.4] | 27.59 [10.3, 44.8] | 3.45 [0.0, 10.3] | 17.24 [3.4, 31.0] |
| Overall full-call exact | 76.55 | 77.24 | 20.69 | 64.14 |
| Irrelevance accuracy ( ) | 62.1 | 31.0 | 89.7 | 6.9 |
| English | Tajik | |||||
|---|---|---|---|---|---|---|
| Stage | Tag | JSON | Other | Tag | JSON | Other |
| Base | 154 | 0 | 20 | 83 | 12 | 79 |
| CPT epoch 1 | 1 | 107 | 66 | 0 | 52 | 122 |
| CPT epoch 2 | 0 | 60 | 114 | 0 | 37 | 137 |
| SFT epoch 1 (released) | 168 | 0 | 6 | 171 | 0 | 3 |
| English | Tajik | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Stage | Full-call exact | Function name | Full-call exact | Function name | ||||||
| Str. | Len. | Inf. | Str. | Len. | Str. | Len. | Inf. | Str. | Len. | |
| Base | 76.55 | 76.55 | 76.55 | 85.58 | 85.58 | 20.69 | 31.72 | 32.41 | 40.38 | 61.54 |
| CPT epoch 1 | 0.00 | 35.17 | 48.28 | 0.48 | 34.62 | 0.00 | 6.90 | 15.17 | 0.00 | 10.58 |
| CPT epoch 2 | 0.00 | 10.34 | 20.00 | 0.00 | 9.13 | 0.00 | 6.90 | 9.66 | 0.00 | 9.13 |
| SFT epoch 1 (released) | 77.24 | 77.24 | 77.24 | 89.42 | 89.42 | 64.14 | 64.14 | 64.14 | 87.98 | 87.98 |
| Stage | Belebele (tg) | Tajik curated | MMLU (en) |
|---|---|---|---|
| Base | 37.6 [34.4, 40.8] | 28.0 [24.7, 31.5] | 60.8 [60.0, 61.6] |
| CPT final (epoch 3) | 36.6 [33.4, 39.7] | 33.0 [29.5, 36.7] | 49.5 [48.7, 50.3] |
| SFT epoch 1 (released) | 40.0 [36.8, 43.2] | 35.0 [31.5, 38.7] | 52.5 [51.7, 53.3] |
| SFT epoch 2 | 40.9 [37.8, 44.0] | 35.0 [31.4, 38.7] | 52.5 [51.7, 53.4] |
Appendix figures & tables6 assets
Supplementary material from the paper’s appendix.
Appendix
| Setting | CPT | SFT epoch 1 | SFT epoch 2 |
|---|---|---|---|
| Starting weights | LFM2.5-2.6B-Base | CPT merged | SFT e1 merged |
| Adapter | LoRA, rsLoRA | LoRA, rsLoRA | LoRA, rsLoRA |
| LoRA rank / alpha | 32 / 32 | 32 / 32 | 32 / 32 |
| Target modules | q_proj, k_proj, v_proj, out_proj, in_proj, w1, w2, w3 | ||
| Sequence length | 4,096 | 4,096 | 4,096 |
| Sample packing | true | false | false |
| CPT source | Documents | Share (%) |
|---|---|---|
| HPLT 2.0 cleaned | 441,838 | 27.4 |
| FineWeb-2 | 447,146 | 27.7 |
| MADLAD-400 | 276,211 | 17.1 |
| C4 | 217,081 | 13.4 |
| Tajik Wikipedia corpus | 50,024 | 3.1 |
| Shahnameh corpus | 8 | 0.0 |
| SFT component | Rows | Share (%) |
|---|---|---|
| glaive-function-calling-v2 | 54,859 | |
| hermes-function-calling-v1, func_calling | 1,090 | |
| hermes-function-calling-v1, func_calling_singleturn | 1,090 | |
| hermes-function-calling-v1, glaive_func_calling | 4,342 | |
| ToolACE | 9,245 | |
| Tool-call rows after dedup | 70,626 |
| Stage | Lang | Fn name | Arg key | Arg value | Full call | Irrel. | Valid parse | Extra call |
|---|---|---|---|---|---|---|---|---|
| Base | EN | 85.58 | 81.03 | 82.50 | 76.55 | 62.1 | 100.00 | 4.14 |
| TG | 40.38 | 36.10 | 30.57 | 20.69 | 89.7 | 97.59 | 7.59 | |
| SFT epoch 1 (released) | EN | 89.42 | 83.61 | 86.92 | 77.24 | 31.0 | 97.62 | 2.76 |
| TG | 87.98 | 82.87 | 80.48 | 64.14 | 6.9 | 100.00 | 2.76 | |
| SFT epoch 2 | EN | 89.42 | n/a | 86.74 | 76.55 | 31.0 | 98.20 | 2.76 |
| TG | 88.46 | n/a | 80.29 | 63.45 | 10.3 | 100.00 | 2.76 |
| Category | Tajik request | Offered tools | Gold call |
|---|---|---|---|
| Single | Ба ман дар бораи филми ’Interstellar’ маълумот диед | movie_details.brief | movie_details.brief(title=’Interstellar’) |
| Parallel | Агар ман сафари худро аз Ню-Йорк сар карда, ба Лос-Анелес, сипас аз Лос-Анелес ба Майами ва дар ниоят аз Майами ба Ню-Йорк равам, масофаи умумии километро чӣ гуна аст? | geo_distance.calculate | geo_distance.calculate(start_location=’New York’, end_location=’Los Angeles’, units=’kilometers’); geo_distance.calculate(start_location=’Los Angeles’, end_location=’Miami’, units=’kilometers’); geo_distance.calculate(start_location=’Miami’, end_location=’New York’, units=’kilometers’) |
| Irrelevance | Оё шумо метавонед филми хуберо барои тамошо тавсия диед? | word_count | (no call) |
| Multi-turn (2nd turn) | Азбаски мо ама тайёрем, оё шумо метавонед зуд фишори чархоро тафтиш кунед, то боварӣ осил кунед, ки ама чиз барои сафари мо бехатар аст? | 31 tools, including check_tire_pressure | check_tire_pressure() |
LLM Tool Use
Large language model tool use studies how models select, call, and coordinate external tools to extend their reasoning and take actions.
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