Claude Fable 5.1 vs Claude Opus 5.5
O Claude Fable 5.1 é disponibilizado por convite. Os valores abaixo são as tarifas em tempo real, mas as chamadas exigem uma permissão de workspace primeiro; solicite-nos acesso antes de desenvolver com base nesta comparação.
Qual usar, quando
Estes dois modelos da Anthropic alinham-se quase exatamente nos fatos: ambos recebem texto e imagem e retornam texto, ambos oferecem um contexto de 1000000-token com o máximo de 128000 de saída, ambos possuem chat, código, pensamento, ferramentas e raciocínio, e nenhum deles permite que o pensamento seja desativado. A diferença é a tabela de preços, onde o claude-fable-5-1 custa $10 de entrada e $50 de saída contra $4 e $20 do claude-opus-5-5, 2.5x mais em ambas as pontas, além de $0.25 contra $0.2 em leituras de cache. Escolha o claude-opus-5-5, lançado em 2026-09-22, para o mesmo escopo a um custo menor, e escolha o claude-fable-5-1 apenas se você já estiver padronizado nele.
Benchmarks
9 medidos em ambos.
Publicado pelos fornecedores: Alibaba (Qwen) Anthropic ByteDance DeepSeek Google MiniMax Moonshot OpenAI Tencent Z.ai
Preços
| Claude Fable 5.1 | Claude Opus 5.5 | Δ | |
|---|---|---|---|
| Entrada / 1M tokens | $10 | $4 | 2.5× |
| Saída / 1M tokens | $50 | $20 | 2.5× |
| Leitura de cache / 1M tokens | $0.25 | $0.2 | 1.3× |
| Escrita de cache | 1.25x (5m) / 2x (1h) | 1.25x (5m) / 2x (1h) | - |
Tarifas do catálogo em tempo real no momento do build; a página de cada modelo contém o cartão atual.
Onde eles se posicionam - preço de entrada por 1M tokens entre todos os 74 modelos de chat nesta unidade de cobrança (escala logarítmica)
Capacidades
| Claude Fable 5.1 | Claude Opus 5.5 | |
|---|---|---|
| Uso de ferramentas | sim | sim |
| Controle de raciocínio | sempre ativo | sempre ativo |
| Saída estruturada | sim | sim |
| Cache de prompt | explícito (você marca o prefixo) | explícito (você marca o prefixo) |
| Tempo de vida do cache | 5m default, 1h option | 5m default, 1h option |
| Prefixo mínimo em cache | 1024 tokens | 1024 tokens |
Especificações
| Claude Fable 5.1 | Claude Opus 5.5 | |
|---|---|---|
| Modalidades de entrada | texto imagem | texto imagem |
| Modalidades de saída | texto | texto |
| Lançamento | 2026-09-01 | 2026-09-22 |
| Corte de conhecimento | 2026-06 | 2026-06 |
| Janela de contexto | 1M | 1M |
| Saída máxima | 128K | 128K |
| Parâmetro de raciocínio | output_config.effort (thinking is adaptive-only and always on) | output_config.effort |
| Valores aceitos | effort
| output_config.effort
|
| Padrão | thinking always on (adaptive) effort
| medium |
As especificações são transcritas da documentação de cada fornecedor; uma linha que um fornecedor não publica é omitida em vez de ser inferida. Fontes completas: Claude Fable 5.1 · Claude Opus 5.5
Um prompt, ambos os modelos - medidos pelo gateway
Claude Fable 5.1 passou · 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.
saída 186 tok latência 3.2 s
Claude Opus 5.5 passou · 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.
saída 263 tok (+102 pensamento) latência 5.7 s
Cumprimento da instrução (exatamente três frases - contáveis), ajuste ao público (registro de CFO), e a lacuna de cobrança do pensamento oculto que os medidores de tokens abaixo expõem.
Claude Fable 5.1 passou · 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). […]
saída 882 tok (+507 pensamento) latência 3.4 s
Claude Opus 5.5 passou · 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. […]
saída 723 tok (+303 pensamento) latência 10.4 s
Se a correção é de fato certa (executável), a densidade da explicação, e a eficiência em tokens numa tarefa delimitada.
Claude Fable 5.1 passou · 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`.
saída 633 tok (+349 pensamento) latência 3.8 s
Claude Opus 5.5 passou · 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.
saída 829 tok (+488 pensamento) latência 10.9 s
Obediência ao esquema (sem campos inventados), pressão de alucinação (guidance é explicitamente retida), e diferenças no caminho de saída estruturada.
Claude Fable 5.1 passou · 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.
saída 1722 tok (+1463 pensamento) latência 2.9 s
Claude Opus 5.5 passou · 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.
saída 1263 tok (+1007 pensamento) latência 13.5 s
Obediência às restrições (orçamento de palavras, lista de palavras proibidas, a única pergunta), impressão digital de estilo, e controle de comprimento.
Alterne entre eles com uma linha
Ambos os IDs estão em todas as abas abaixo - o par de linhas destacado é a única edição. Mesmo endpoint, mesma chave, mesmo formato de requisição.
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", # descomente esta linha, comente a linha acima
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", // descomente esta linha, comente a linha acima
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", # descomente esta linha, comente a linha acima
"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", // descomente esta linha, comente a linha acima
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") // descomente esta linha, comente a linha acima
.addUserMessage("Summarize this diff")
.reasoningEffort(ReasoningEffort.MEDIUM)
.build());
System.out.println(resp.choices().get(0).message().content().orElse(""));FAQ
Qual é mais barato, Claude Fable 5.1 ou Claude Opus 5.5?
Claude Opus 5.5 é mais barato em entrada / 1m tokens ($4 vs $10, com 2.5× de diferença). Outras linhas podem apontar para o outro lado - a tabela acima traz o quadro completo, e o custo real depende do seu mix.
Posso fazer um teste A/B de Claude Fable 5.1 contra Claude Opus 5.5 sem duas integrações?
Sim. Ambos são servidos pelo mesmo endpoint compatível com OpenAI com uma única chave de API - a troca é uma alteração de uma linha na string do modelo, de modo que você pode rotear uma fração do tráfego para cada um e comparar as faturas diretamente.
Claude Fable 5.1 e Claude Opus 5.5 suportam prompt caching?
Sim - ambos cobram leituras em cache abaixo da sua taxa de entrada, então cargas de trabalho com warm-prefix custam menos do que as taxas listadas sugerem. As linhas exatas de leitura em cache estão na tabela de preços acima.