Claude Sonnet 4.6 Behavioral Fingerprint
How Anthropic's Claude Sonnet 4.6 answers one-word probe questions at temperature 1.0 — random numbers, colors, animals, coin flips — measured over 450 valid samples in the open dataset of "One Token Is Enough" (arXiv:2607.10252).
Vendor
Anthropic
Data generated
2026-07-08
Probe cells
15
Valid samples
450
Randomness score
10 / 100
Mean normalized entropy across cells, 0–100. 100 would be a uniform-random baseline; real models score far lower.
Signature answers
Favorite random number (1–100)
47
17 / 30 answers
Favorite color
blue
30 / 30 answers
Coin flip: heads
97%
Share of heads across coin-flip cells.
Answer distributions by probe cell
Empirical distributions of normalized one-word answers, per task and language. H is the Shannon entropy in bits; the uniform baseline is log2 of the answer-domain size.
Coin flip · English
n = 30 · H = 0.35 bit · uniform baseline 1.00 bit
| Answer | Count | Share |
|---|---|---|
| heads | 28 | 93.3% |
| tails | 2 | 6.7% |
Coin flip · Chinese
n = 30 · H = 0.00 bit · uniform baseline 1.00 bit
| Answer | Count | Share |
|---|---|---|
| heads | 30 | 100.0% |
Favorite number · English
n = 30 · H = 0.78 bit · uniform baseline 13.29 bit
| Answer | Count | Share |
|---|---|---|
| 42 | 23 | 76.7% |
| 7 | 7 | 23.3% |
Favorite number · Chinese
n = 30 · H = 0.00 bit · uniform baseline 13.29 bit
| Answer | Count | Share |
|---|---|---|
| 7 | 30 | 100.0% |
Random animal · English
n = 30 · H = 0.85 bit · uniform baseline 5.64 bit
| Answer | Count | Share |
|---|---|---|
| elephant | 24 | 80.0% |
| giraffe | 5 | 16.7% |
| capybara | 1 | 3.3% |
Random animal · Chinese
n = 30 · H = 1.31 bit · uniform baseline 5.64 bit
| Answer | Count | Share |
|---|---|---|
| 狐狸 | 21 | 70.0% |
| 熊猫 | 5 | 16.7% |
| 斑马 | 2 | 6.7% |
| 企鹅 | 2 | 6.7% |
Random city · English
n = 30 · H = 0.00 bit · uniform baseline 5.64 bit
| Answer | Count | Share |
|---|---|---|
| tokyo | 30 | 100.0% |
Random city · Chinese
n = 30 · H = 0.00 bit · uniform baseline 5.64 bit
| Answer | Count | Share |
|---|---|---|
| 成都 | 30 | 100.0% |
Random color · English
n = 30 · H = 0.00 bit · uniform baseline 4.91 bit
| Answer | Count | Share |
|---|---|---|
| blue | 30 | 100.0% |
Random color · Chinese
n = 30 · H = 0.95 bit · uniform baseline 4.91 bit
| Answer | Count | Share |
|---|---|---|
| 青 | 19 | 63.3% |
| 紫 | 11 | 36.7% |
Random letter · English
n = 30 · H = 0.97 bit · uniform baseline 4.70 bit
| Answer | Count | Share |
|---|---|---|
| k | 18 | 60.0% |
| m | 12 | 40.0% |
Random number 1-10 · English
n = 30 · H = 0.00 bit · uniform baseline 3.32 bit
| Answer | Count | Share |
|---|---|---|
| 7 | 30 | 100.0% |
Random number 1-10 · Chinese
n = 30 · H = 0.00 bit · uniform baseline 3.32 bit
| Answer | Count | Share |
|---|---|---|
| 7 | 30 | 100.0% |
Random number 1-100 · English
n = 30 · H = 0.99 bit · uniform baseline 6.64 bit
| Answer | Count | Share |
|---|---|---|
| 47 | 17 | 56.7% |
| 42 | 13 | 43.3% |
Random number 1-100 · Chinese
n = 30 · H = 0.65 bit · uniform baseline 6.64 bit
| Answer | Count | Share |
|---|---|---|
| 47 | 25 | 83.3% |
| 42 | 5 | 16.7% |
Want to verify your API really serves Claude Sonnet 4.6?
Point the free fingerprint checker at your endpoint: it samples the same probe questions from your browser and compares the distributions against this reference. Your API key never leaves your browser.
Verify your endpointData source & license
Distributions: Tomáš Bruckner, "One Token Is Enough" (arXiv:2607.10252), official dataset Zenodo DOI 10.5281/zenodo.21278557, licensed CC-BY-4.0. Collected via OpenRouter at temperature 1.0 under the paper's fixed minimal one-word system prompt; answer keys are re-normalized with the checker's pipeline (color aliases, number words, coin h/t) so live probes are directly comparable.