Claude Fable 5.1 vs Claude Opus 5.5
Claude Fable 5.1 è disponibile su invito. Le cifre sottostanti sono le tariffe in tempo reale, ma le chiamate richiedono prima un'autorizzazione per il workspace; richiedici l'accesso prima di basare il tuo sviluppo su questo confronto.
Quale scegliere e quando
Questi due modelli Anthropic si allineano quasi esattamente sui fatti: entrambi accettano testo e immagini in input e restituiscono testo in output, entrambi offrono un contesto da 1000000-token con 128000 di output massimo, entrambi includono chat, codice, thinking, strumenti e ragionamento, e nessuno dei due permette di disabilitare il thinking. La differenza sta nel tariffario, dove claude-fable-5-1 costa $10 per l'input e $50 per l'output contro i $4 e $20 di claude-opus-5-5, 2.5x in più su entrambi i fronti, oltre a $0.25 contro $0.2 per le letture della cache. Scegli claude-opus-5-5, rilasciato il 2026-09-22, per avere le stesse specifiche a un costo inferiore, e scegli claude-fable-5-1 solo se sei già standardizzato su di esso.
Benchmark
9 misurati su entrambi.
Dati pubblicati dai fornitori: Alibaba (Qwen) Anthropic ByteDance DeepSeek Google MiniMax Moonshot OpenAI Tencent Z.ai
Prezzi
| Claude Fable 5.1 | Claude Opus 5.5 | Δ | |
|---|---|---|---|
| Input / 1M token | $10 | $4 | 2.5× |
| Output / 1M token | $50 | $20 | 2.5× |
| Lettura cache / 1M token | $0.25 | $0.2 | 1.3× |
| Scrittura in cache | 1.25x (5m) / 2x (1h) | 1.25x (5m) / 2x (1h) | - |
Le tariffe provengono dal catalogo live al momento della build; la pagina di ciascun modello riporta la scheda attuale.
Dove si posizionano - prezzo di input per 1M di token rispetto a tutti gli 74 modelli chat con questa unità di fatturazione (scala logaritmica)
Capacità
| Claude Fable 5.1 | Claude Opus 5.5 | |
|---|---|---|
| Utilizzo dei tool | sì | sì |
| Controllo del ragionamento | sempre attivo | sempre attivo |
| Output strutturato | sì | sì |
| Prompt caching | esplicito (contrassegni il prefisso) | esplicito (contrassegni il prefisso) |
| Durata della cache | 5m default, 1h option | 5m default, 1h option |
| Prefisso minimo in cache | 1024 token | 1024 token |
Specifiche
| Claude Fable 5.1 | Claude Opus 5.5 | |
|---|---|---|
| Modalità di input | testo immagine | testo immagine |
| Modalità di output | testo | testo |
| Rilascio | 2026-09-01 | 2026-09-22 |
| Cutoff di conoscenza | 2026-06 | 2026-06 |
| Finestra di contesto | 1M | 1M |
| Output massimo | 128K | 128K |
| Parametro thinking | output_config.effort (thinking is adaptive-only and always on) | output_config.effort |
| Valori accettati | effort
| output_config.effort
|
| Predefinito | thinking always on (adaptive) effort
| medium |
Le specifiche sono trascritte dalla documentazione di ciascun fornitore; una riga che un fornitore non pubblica viene omessa anziché essere dedotta. Fonti complete: Claude Fable 5.1 · Claude Opus 5.5
Un solo prompt, entrambi i modelli - misurati attraverso il gateway
Claude Fable 5.1 superato · 3 sentences
When we enabled reasoning, the model started generating a long chain of internal "thinking" tokens before producing each answer, and we're billed for those tokens at the same output rate even though users never see them. In practice, that hidden reasoning often runs several times longer than the visible response, so the total tokens per request roughly doubled while the number of requests stayed flat. The upside is measurably better accuracy on complex tasks, so the right conversation is whether that quality gain justifies the cost—and if not, we can restrict reasoning to the workflows that actually need it rather than turning it on globally.
out 186 tok latenza 3.2 s
Claude Opus 5.5 superato · 3 sentences
When we turned on reasoning, the model began "thinking out loud" before each answer, generating thousands of internal working tokens that users never see but that we are billed for just like the final response. Those hidden tokens are charged at the output rate, typically the most expensive rate, so the same question with the same visible answer now costs roughly twice as much or more. We can bring the bill back down without losing the quality gains by capping the reasoning budget and reserving reasoning mode for the complex tasks that actually benefit from it.
out 263 tok (+102 ragionamento) latenza 5.7 s
Rispetto dell'istruzione (esattamente tre frasi - contabili), adattamento al pubblico (registro da CFO), e il divario di fatturazione del pensiero nascosto che i contatori di token qui sotto rivelano.
Claude Fable 5.1 superato · 8/8 cases
```python def longest_run(xs): if not xs: return 0 best = cur = 1 for i in range(1, len(xs)): cur = cur + 1 if xs[i] == xs[i - 1] else 1 best = max(best, cur) return best ``` The bug is that `cur` counts *matches between adjacent elements* rather than *elements in the run*: it starts at 0 and only increments when `xs[i] == xs[i-1]`, so a run of length k produces a count of k−1. That's why a single element returns 0 instead of 1, and why every other run also comes out one short — the "misses runs at the end" reports are the same off-by-one seen on inputs like `[1, 2, 2]`, where the trailing run of length 2 is reported as 1 (the original code does update `best` inside the loop, so end-of-list runs aren't actually skipped, just undercounted). […]
out 882 tok (+507 ragionamento) latenza 3.4 s
Claude Opus 5.5 superato · 8/8 cases
```python def longest_run(xs): if not xs: return 0 best = 1 cur = 1 for i in range(1, len(xs)): if xs[i] == xs[i - 1]: cur += 1 best = max(best, cur) else: cur = 1 return best ``` **Explanation:** The original code counted *matching adjacent pairs* rather than *items in a run*. Both `cur` and `best` started at 0, and `cur` reset to 0 on a mismatch, so a run of length *n* was reported as *n − 1*. For a single-element list the loop never executes, so it returned 0 instead of 1. For `[5, 5]` it returned 1 instead of 2. The fix treats every element as the start of a run of length 1: `best` and `cur` start at 1, and `cur` resets to 1 (not 0) when the value changes. An explicit check returns 0 for an empty list. The "misses runs at the last index" reports are the same off-by-one bug rather than a separate one. […]
out 723 tok (+303 ragionamento) latenza 10.4 s
Se la correzione è davvero giusta (eseguibile), la densità della spiegazione, e l'efficienza in token su un compito delimitato.
Claude Fable 5.1 superato · 5/5 fields, guidance null
```json { "company": "Meridian Robotics", "quarter": "Q3 (September quarter)", "revenue_usd_m": 412, "growth_pct": 11, "guidance": null } ``` Notes on judgment calls (not part of the object): - **revenue_usd_m**: The text says "412 for the topline" but never states the currency or that the figure is in millions; it's also on a constant-currency basis and prefaced with "call it," so it's approximate. If you want strict literalism, this should be `null`. - **growth_pct**: "Eleven and change" means slightly above 11%; the exact figure isn't given. - **quarter**: "September quarter" is Q3 on a calendar basis, consistent with the reference to a pending Q4 close. - **guidance**: Explicitly withheld, so `null`.
out 633 tok (+349 ragionamento) latenza 3.8 s
Claude Opus 5.5 superato · 5/5 fields, guidance "Withheld pending Q4 close"
```json { "company": "Meridian Robotics", "quarter": "September quarter", "revenue_usd_m": 412, "growth_pct": 11, "guidance": "Withheld pending Q4 close" } ``` **Judgment calls to check:** - **quarter**: Kept as "September quarter" rather than "Q3", since the fiscal calendar isn't stated. The text mentions an upcoming "Q4 close," so it may be fiscal Q3, but that's not certain. - **revenue_usd_m**: The text says only "412 for the topline." It doesn't state currency or units, and the figure is on a constant-currency basis, not reported USD. USD millions is an assumption. Use `null` if you need strictly stated values. - **growth_pct**: The source says "eleven and change," so the true figure is slightly above 11. 11 is an approximation. - **guidance**: Guidance was explicitly withheld. I recorded that rather than `null`, since the text addresses it directly.
out 829 tok (+488 ragionamento) latenza 10.9 s
Aderenza allo schema (nessun campo inventato), pressione di allucinazione (guidance è esplicitamente sospesa), e differenze nel percorso di output strutturato.
Claude Fable 5.1 superato · 121 words, 0 banned, 1 question
**Introducing Cross-Provider Prompt Caching for the Gateway.** Starting today, your API gateway can cache prompts once and reuse them across OpenAI, Anthropic, Google, and any other provider you route to. Long system instructions, retrieval context, and few-shot examples are stored at the gateway layer, so switching models no longer means paying to resend the same tokens. Why send the same 8,000-token preamble to three different vendors when you could send it once? Our cache normalizes prompt segments, fingerprints them, and serves matching prefixes from memory before the request ever reaches an upstream API. Early customers report token costs falling by 30 to 60 percent on high-volume workloads, with median latency dropping alongside. Available today on all Team and Enterprise plans.
out 1722 tok (+1463 ragionamento) latenza 2.9 s
Claude Opus 5.5 superato · 120 words, 0 banned, 1 question
Today we're launching Cross-Provider Prompt Caching for our API gateway. Why pay twice for the same context? Our gateway now stores repeated prompt prefixes, system instructions, and document chunks, then reuses them whether your request goes to OpenAI, Anthropic, Google, or an open-source model. Teams running retrieval pipelines or long agent loops can cut token costs by up to 60 percent and trim latency on every cached call. Setup takes one configuration flag; no code changes are required. Cache rules respect tenant boundaries, expire on your schedule, and log every hit for audit review. Dashboards show savings by provider, route, and application in real time. Cross-Provider Prompt Caching is available on all Pro and Enterprise plans. Turn it on today.
out 1263 tok (+1007 ragionamento) latenza 13.5 s
Rispetto dei vincoli (budget di parole, elenco di parole vietate, l'unica domanda), impronta stilistica, e controllo della lunghezza.
Passa dall'uno all'altro con una sola riga
Entrambi gli id sono presenti in ogni scheda qui sotto - la coppia di righe evidenziata è l'unica modifica. Stesso endpoint, stessa chiave, stessa struttura della richiesta.
from openai import OpenAI
client = OpenAI(
base_url="https://synthorai.io/v1",
api_key="sk-syn-...",
)
resp = client.chat.completions.create(
model="claude-fable-5-1",
# model="claude-opus-5-5", # decommenta questa riga, commenta quella sopra
messages=[{"role": "user", "content": "Summarize this diff"}],
reasoning_effort="medium",
)
print(resp.choices[0].message.content)import OpenAI from "openai";
const client = new OpenAI({
baseURL: "https://synthorai.io/v1",
apiKey: "sk-syn-...",
});
const resp = await client.chat.completions.create({
model: "claude-fable-5-1",
// model: "claude-opus-5-5", // decommenta questa riga, commenta quella sopra
messages: [{ role: "user", content: "Summarize this diff" }],
reasoning_effort: "medium",
});
console.log(resp.choices[0].message.content);curl https://synthorai.io/v1/chat/completions \
-H "Authorization: Bearer sk-syn-..." \
-H "Content-Type: application/json" \
-d '{
"model": "claude-fable-5-1",
# "model": "claude-opus-5-5", # decommenta questa riga, commenta quella sopra
"messages": [{"role": "user", "content": "Hello"}],
"reasoning_effort": "medium"
}'package main
import (
"context"
"fmt"
"github.com/openai/openai-go/v3"
"github.com/openai/openai-go/v3/option"
)
func main() {
client := openai.NewClient(
option.WithBaseURL("https://synthorai.io/v1"),
option.WithAPIKey("sk-syn-..."),
)
resp, _ := client.Chat.Completions.New(context.TODO(), openai.ChatCompletionNewParams{
Model: "claude-fable-5-1",
// Model: "claude-opus-5-5", // decommenta questa riga, commenta quella sopra
Messages: []openai.ChatCompletionMessageParamUnion{
openai.UserMessage("Summarize this diff"),
},
ReasoningEffort: openai.ReasoningEffortMedium,
})
fmt.Println(resp.Choices[0].Message.Content)
}import com.openai.client.OpenAIClient;
import com.openai.client.okhttp.OpenAIOkHttpClient;
import com.openai.models.chat.completions.*;
import com.openai.models.ReasoningEffort;
OpenAIClient client = OpenAIOkHttpClient.builder()
.baseUrl("https://synthorai.io/v1")
.apiKey("sk-syn-...")
.build();
ChatCompletion resp = client.chat().completions().create(
ChatCompletionCreateParams.builder()
.model("claude-fable-5-1")
// .model("claude-opus-5-5") // decommenta questa riga, commenta quella sopra
.addUserMessage("Summarize this diff")
.reasoningEffort(ReasoningEffort.MEDIUM)
.build());
System.out.println(resp.choices().get(0).message().content().orElse(""));FAQ
Qual è più economico, Claude Fable 5.1 o Claude Opus 5.5?
Claude Opus 5.5 è più economico per input / 1m token ($4 contro $10, 2.5× di differenza). Altre righe potrebbero indicare il contrario - la tabella sopra riporta la scheda completa, e il costo reale dipende dal tuo mix.
Posso fare un A/B test di Claude Fable 5.1 contro Claude Opus 5.5 senza due integrazioni?
Sì. Entrambi sono serviti tramite lo stesso endpoint compatibile con OpenAI con una singola chiave API - il passaggio richiede la modifica della stringa del modello in una sola riga, quindi puoi instradare una frazione del traffico verso ciascuno e confrontare direttamente le fatture.
Claude Fable 5.1 e Claude Opus 5.5 supportano il prompt caching?
Sì - entrambi fatturano le letture in cache a un prezzo inferiore rispetto alla loro tariffa di input, quindi i carichi di lavoro con warm-prefix costano meno di quanto suggeriscano le tariffe di listino. Le righe esatte per la lettura in cache si trovano nella tabella dei prezzi qui sopra.