anthropic/claude-3-haiku behavioral LLM fingerprint
This page breaks down the exact reference that VerifyLLMAPI uses for anthropic/claude-3-haiku: 120 normalized answers across eight low-entropy probes, plus its nearest enrolled models by mean Jensen–Shannon divergence.
Fingerprint summary
- Reference answers
- 120
- Samples per cell
- 15–15
- Nearest model
- mistralai/mistral-medium-3-5
- Nearest mean JSD
- 0.621831
The most concentrated cell was animal-random|en: giraffe held 40.0% of its answers and entropy measured 2.206 bits. The broadest cell was letter-random|zh at 3.907 bits.
Against the closest enrolled model, letter-random|zh contributed the largest cell distance at JSD 0.908170. This is a descriptive comparison, not proof that either API route serves a named checkpoint.
Completeness: the author dataset allows up to 15 valid answers per selected cell in reference half A. This model contains 120/120 across the eight cells. We show the actual denominator for every share.
The eight test requests
The research pipeline sent each user prompt with a one-answer system constraint, temperature 1, a 16-token output cap, and reasoning disabled. VerifyLLMAPI uses the same prompt text and normalization target.
| Cell | Task | Exact request text | Normalization and n |
|---|---|---|---|
animal-random|en |
Random animal · English | Name a random animal.System constraintAnswer with a single word or a single number only. Output nothing else: no explanation, no punctuation, no quotation marks. |
word · 15/15 reference samples |
word-random|en |
Random word · English | Name a random word.System constraintAnswer with a single word or a single number only. Output nothing else: no explanation, no punctuation, no quotation marks. |
word · 15/15 reference samples |
animal-random|ru |
Random animal · Russian | Назови случайное животное.System constraintОтвечай только одним словом или одним числом. Не выводи ничего больше: без объяснений, без знаков препинания, без кавычек. |
word · 15/15 reference samples |
animal-random|ar |
Random animal · Arabic | اذكر حيواناً عشوائياً.System constraintأجب بكلمة واحدة أو رقم واحد فقط. لا تكتب أي شيء آخر: لا شرح ولا علامات ترقيم ولا علامات اقتباس. |
word · 15/15 reference samples |
letter-random|zh |
Random character · Chinese | 说出一个随机的汉字。System constraint只用一个词或一个数字回答。不要输出任何其他内容：不要解释，不要标点符号，不要引号。 |
grapheme · 15/15 reference samples |
animal-random|zh |
Random animal · Chinese | 说出一个随机的动物。System constraint只用一个词或一个数字回答。不要输出任何其他内容：不要解释，不要标点符号，不要引号。 |
word · 15/15 reference samples |
letter-random|ar |
Random letter · Arabic | اذكر حرفاً عشوائياً من الحروف الأبجدية.System constraintأجب بكلمة واحدة أو رقم واحد فقط. لا تكتب أي شيء آخر: لا شرح ولا علامات ترقيم ولا علامات اقتباس. |
grapheme · 15/15 reference samples |
color-random|zh |
Random color · Chinese | 说出一个随机的颜色。System constraint只用一个词或一个数字回答。不要输出任何其他内容：不要解释，不要标点符号，不要引号。 |
word · 15/15 reference samples |
Response distributions
These are normalized reference-half counts from the published OpenRouter dataset. The tables contain aggregate values, not user data or a live VerifyLLMAPI scan.
1. animal-random|en
Random animal, English. 15 valid reference answers produced 6 normalized values. The mode was giraffe at 6/15 (40.0%); entropy was 2.206 bits.
| Normalized response | Count | Share |
|---|---|---|
giraffe |
6 | 40.0% |
dog |
4 | 26.7% |
cat |
2 | 13.3% |
dolphin |
1 | 6.7% |
elephant |
1 | 6.7% |
platypus |
1 | 6.7% |
2. word-random|en
Random word, English. 15 valid reference answers produced 13 normalized values. The mode was banana at 2/15 (13.3%); entropy was 3.640 bits.
| Normalized response | Count | Share |
|---|---|---|
banana |
2 | 13.3% |
dog |
2 | 13.3% |
apple |
1 | 6.7% |
butterfly |
1 | 6.7% |
car |
1 | 6.7% |
cat |
1 | 6.7% |
dolphin |
1 | 6.7% |
mango |
1 | 6.7% |
pencil |
1 | 6.7% |
protean |
1 | 6.7% |
serendipity |
1 | 6.7% |
snowflake |
1 | 6.7% |
tree |
1 | 6.7% |
3. animal-random|ru
Random animal, Russian. 15 valid reference answers produced 10 normalized values. The mode was жираф at 4/15 (26.7%); entropy was 3.107 bits.
| Normalized response | Count | Share |
|---|---|---|
жираф |
4 | 26.7% |
лев |
2 | 13.3% |
собака |
2 | 13.3% |
кенгуру |
1 | 6.7% |
коала |
1 | 6.7% |
корова |
1 | 6.7% |
лошадь |
1 | 6.7% |
панда |
1 | 6.7% |
слон |
1 | 6.7% |
🐘 |
1 | 6.7% |
4. animal-random|ar
Random animal, Arabic. 15 valid reference answers produced 9 normalized values. The mode was كلب at 5/15 (33.3%); entropy was 2.816 bits.
| Normalized response | Count | Share |
|---|---|---|
كلب |
5 | 33.3% |
فيل |
3 | 20.0% |
أرنب |
1 | 6.7% |
زبرة |
1 | 6.7% |
ضفدع |
1 | 6.7% |
قط |
1 | 6.7% |
قطة |
1 | 6.7% |
لبؤة |
1 | 6.7% |
🦒 |
1 | 6.7% |
5. letter-random|zh
Random character, Chinese. 15 valid reference answers produced 15 normalized values. The mode was 寺 at 1/15 (6.7%); entropy was 3.907 bits.
| Normalized response | Count | Share |
|---|---|---|
寺 |
1 | 6.7% |
日 |
1 | 6.7% |
木 |
1 | 6.7% |
桃 |
1 | 6.7% |
槽 |
1 | 6.7% |
橘 |
1 | 6.7% |
涟 |
1 | 6.7% |
澜 |
1 | 6.7% |
道 |
1 | 6.7% |
雨 |
1 | 6.7% |
风 |
1 | 6.7% |
飘 |
1 | 6.7% |
馒 |
1 | 6.7% |
鱼 |
1 | 6.7% |
鼎 |
1 | 6.7% |
6. animal-random|zh
Random animal, Chinese. 15 valid reference answers produced 10 normalized values. The mode was 豹 at 3/15 (20.0%); entropy was 3.190 bits.
| Normalized response | Count | Share |
|---|---|---|
豹 |
3 | 20.0% |
狗 |
2 | 13.3% |
狮子 |
2 | 13.3% |
猫 |
2 | 13.3% |
猪 |
1 | 6.7% |
老虎 |
1 | 6.7% |
虎 |
1 | 6.7% |
象 |
1 | 6.7% |
鸡 |
1 | 6.7% |
鼠 |
1 | 6.7% |
7. letter-random|ar
Random letter, Arabic. 15 valid reference answers produced 12 normalized values. The mode was س at 2/15 (13.3%); entropy was 3.507 bits.
| Normalized response | Count | Share |
|---|---|---|
س |
2 | 13.3% |
م |
2 | 13.3% |
ه |
2 | 13.3% |
a |
1 | 6.7% |
j |
1 | 6.7% |
q |
1 | 6.7% |
ت |
1 | 6.7% |
ج |
1 | 6.7% |
ز |
1 | 6.7% |
ط |
1 | 6.7% |
ق |
1 | 6.7% |
ل |
1 | 6.7% |
8. color-random|zh
Random color, Chinese. 15 valid reference answers produced 7 normalized values. The mode was 绿色 at 4/15 (26.7%); entropy was 2.606 bits.
| Normalized response | Count | Share |
|---|---|---|
绿色 |
4 | 26.7% |
红 |
3 | 20.0% |
绿 |
3 | 20.0% |
蓝 |
2 | 13.3% |
紫 |
1 | 6.7% |
紫色 |
1 | 6.7% |
蓝色 |
1 | 6.7% |
Three nearest enrolled references
We compute base-2 JSD for each of the eight categorical distributions, then average the eight distances. A lower value means more similar answer frequencies within this product reference. It does not identify an unknown route by itself.
| Rank | Reference model | Mean 8-cell JSD |
|---|---|---|
| 1 | mistralai/mistral-medium-3-5 |
0.621831 |
| 2 | z-ai/glm-5-turbo |
0.625601 |
| 3 | google/gemini-2.5-flash-lite |
0.631602 |
How many live requests does verification use?
| Profile | Cells × samples | Fresh model requests | Same-data EER |
|---|---|---|---|
| Quick, default complete check | 4 × 5 | 20 | 11.8% |
| Standard | 8 × 5 | 40 | 8.1% |
| Paper budget | 8 × 15 | 120 | 6.7% |
The current-Agent workflow starts with quick. Each answer comes from a fresh Codex or Claude Code process that reuses host-managed login. These requests can consume host allowance or provider balance.
What this fingerprint can and cannot show
- The reference records behavior observed through OpenRouter in the author dataset. Provider wrappers, model updates, decoding, and date can move a distribution.
- The author collection set temperature 1 and disabled reasoning. Current-Agent mode labels sampling as a host default because supported Agent CLIs expose no temperature flag.
- The eight high-gap cells and product thresholds use the same public cohort. Their EER values are calibration results, not an independent production accuracy claim.
- A nearest reference is a similarity result. VerifyLLMAPI returns INCONCLUSIVE when the claimed route lacks an enrolled fingerprint.
Primary sources, license, and reproducibility
- Tomas Bruckner, One Token Is Enough: Fingerprinting and Verifying Large Language Models from Single-Token Output Distributions, arXiv:2607.10252v1.
- Author dataset and derived results, DOI 10.5281/zenodo.21278557, CC BY 4.0.
- Author collection and analysis software, DOI 10.5281/zenodo.21278793, MIT.
- VerifyLLMAPI atlas JSON, built from reference
pamela-openrouter-2026-07-8cell-ref-a, SHA-25651f3f63cbcfb56b151055d2d10e36a9cc2f0644cc68b580784853d68951fa866.
Page evidence SHA-256: 5fdf949943309b6ca5f100db5329a8fc92ce292d08cf39f53dfa443daf5bc551. This hash covers the model ID, eight cell metrics, nearest references, and strongest cell difference in the generated atlas.