Claude Fable 5 vs Claude Opus 5
Cuál usar y cuándo — veredicto seleccionado, no una tabla de benchmarks
La propia bifurcación en el camino de Anthropic: Opus 5 a $5/$25 con pensamiento adaptativo que se puede desactivar, Fable 5 a $10/$50 donde el pensamiento es estructural y siempre está activo. Si su carga de trabajo se beneficia de desactivar la deliberación en llamadas simples, Opus 5 cuesta la mitad y obedece; Fable 5 es para trabajos donde nunca desea que el modelo omita el pensamiento.
Precios
| Claude Fable 5 | Claude Opus 5 | Δ | |
|---|---|---|---|
| Entrada / 1M tokens | $10 | $5 | 2× |
| Salida / 1M tokens | $50 | $25 | 2× |
| Lectura de caché / 1M tokens | $1 | $0.5 | 2× |
| Escritura en caché | 1.25x (5m) / 2x (1h) | 1.25x (5m) / 2x (1h) | — |
Tarifas del catálogo en vivo en el momento de la compilación; la página de cada modelo incluye la ficha actualizada.
Dónde se sitúan — precio de entrada por 1M de tokens en todos los 63 modelos de chat en esta unidad de facturación (escala logarítmica)
Capacidades
| Claude Fable 5 | Claude Opus 5 | |
|---|---|---|
| Uso de herramientas | sí | sí |
| Control de pensamiento | siempre activo | configurable |
| Salida estructurada | sí | sí |
| Caché de prompt | explícito (marcas el prefijo) | explícito (marcas el prefijo) |
| Tiempo de vida de la caché | 5m default, 1h option | 5m default, 1h option |
| Prefijo mínimo en caché | 1024 tokens | 1024 tokens |
Especificaciones
| Claude Fable 5 | Claude Opus 5 | |
|---|---|---|
| Modalidades de entrada | texto imagen | texto imagen |
| Modalidades de salida | texto | texto |
| Lanzamiento | 2026-06-09 | 2026-07-24 |
| Límite de conocimiento | 2026-01 | 2026-05 |
| Ventana de contexto | 1M | 1M |
| Salida máxima | 128K | 128K |
| Parámetro de pensamiento | output_config.effort (thinking.type is adaptive-only and needs no configuration) |
|
| Valores aceptados | effort
both "enabled" and "disabled" return 400 | thinking.type
effort
|
| Predeterminado | thinking always on (adaptive) effort
| thinking on effort
|
Las especificaciones se transcriben de la documentación de cada proveedor; si un proveedor no publica una fila, se omite en lugar de inferirse. Fuentes completas: Claude Fable 5 · Claude Opus 5
Un prompt, ambos modelos — medido a través del gateway
Claude Fable 5 superado · 3 sentences
When we enabled reasoning, the model began generating extensive internal "thinking" tokens before each answer, and those tokens are billed as output even though users never see them. Output tokens typically cost several times more than input tokens, so adding thousands of hidden reasoning tokens per request effectively multiplied our per-query cost. In short, we're paying for a much longer response behind the scenes in exchange for higher answer quality, and we can manage this by tuning reasoning effort levels or reserving reasoning mode for complex tasks only.
salida 228 tok latencia 6.7 s
Claude Opus 5 superado · 3 sentences
When reasoning is enabled, the model generates a hidden chain of "thinking" tokens before it writes the visible answer, and those internal tokens are billed at the output rate even though no one ever sees them — commonly 3–10x more tokens than the response itself. Because output tokens are priced several times higher than input tokens, that added volume hits us at our most expensive rate, which is why the bill roughly doubled while our request count stayed flat. The spend is controllable: we can cap the reasoning budget per call, route only genuinely hard requests to reasoning mode and cheaper models for the rest, and track cost per successfully completed task rather than cost per token, since a single correct answer usually beats three cheap retries plus human cleanup.
salida 529 tok latencia 9.0 s
Seguimiento de la instrucción (exactamente tres frases — contables), adaptación a la audiencia (registro de CFO), y la brecha de facturación por pensamiento oculto que los medidores de tokens de abajo dejan ver.
Claude Fable 5 superado · 8/8 cases
## Fixed code ```python def longest_run(xs): if not xs: return 0 best = cur = 1 for i in range(1, len(xs)): if xs[i] == xs[i - 1]: cur += 1 else: cur = 1 best = max(best, cur) return best ``` ## Explanation The original function counts **adjacent equal pairs** rather than **items in a run**: a run of length *n* contains only *n − 1* equal neighbor pairs, so every result is off by one — a single-element list yields 0 instead of 1, and `[1, 2, 2]` yields 1 instead of 2 (which callers perceive as "missing" the run at the end). The fix is to initialize both `cur` and `best` to 1 (any nonempty list has a run of at least length 1), reset `cur` to 1 rather than 0 when
salida 531 tok latencia 12.5 s
Claude Opus 5 superado · 8/8 cases
## Fixed version ```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 else: cur = 1 if cur > best: best = cur return best ``` ## The bug The counters were tracking the wrong quantity: `cur` counted *matching adjacent pairs* rather than *elements in the current run*, and both counters started at `0` instead of `1`. Since a run of length *n* contains only *n − 1* adjacent equal pairs, every result came back one too small — `[1, 1]` returned 1, `[3, 3, 3]` returned 2 — and a single-element list returned 0 because the loop body never executed and `best` kept its initial value of `0`. […]
salida 1094 tok latencia 16.1 s
Si el arreglo es realmente correcto (ejecutable), la densidad de la explicación, y la eficiencia en tokens sobre una tarea acotada.
Claude Fable 5 superado · 5/5 fields, guidance null
```json { "company": "Meridian Robotics", "quarter": "Q3 (September quarter)", "revenue_usd_m": 412, "growth_pct": 11, "guidance": null } ``` Notes on interpretation: "up eleven and change" is rendered as 11 (the precise figure isn't stated), and guidance is null because it was explicitly withheld.
salida 192 tok latencia 6.5 s
Claude Opus 5 superado · 5/5 fields, guidance "Withheld pending Q4 close"
```json { "company": "Meridian Robotics", "quarter": "Q3", "revenue_usd_m": 412, "growth_pct": 11, "guidance": "Withheld pending Q4 close" } ``` Notes on judgment calls: - **quarter**: "September quarter" is labeled Q3 because the text refers to an upcoming "Q4 close," implying a calendar-aligned fiscal year. No fiscal year is given. - **revenue_usd_m**: 412 is stated as constant-currency and hedged ("call it"), so it's approximate; the currency is not explicitly stated as USD. - **growth_pct**: "up eleven and change" means slightly more than 11, so 11 is a floor rather than an exact figure.
salida 539 tok latencia 7.6 s
Obediencia al esquema (sin campos inventados), presión de alucinación (guidance se retiene explícitamente), y diferencias en la ruta de salida estructurada.
Claude Fable 5 superado · 120 words, 0 banned, 1 question
**Introducing Cross-Provider Prompt Caching for our API Gateway** Starting today, your repeated prompts are cached once and reused across OpenAI, Anthropic, Google, and any other provider you route through the gateway. Instead of paying full token costs every time your application sends the same system prompt or context block, the gateway detects matching prefixes and serves cached results in milliseconds. Why keep spending money and latency on identical requests? Early adopters report cost reductions of up to 60 percent on high-volume workloads, along with faster median response times. Configuration is simple: enable caching in your dashboard, set a TTL, and choose which routes participate. Cache entries are encrypted at rest and never shared between accounts. Available now on all plans.
salida 1173 tok latencia 18.2 s
Claude Opus 5 superado · 123 words, 0 banned, 1 question
**Cross-Provider Prompt Caching** We're introducing Cross-Provider Prompt Caching in the API Gateway. Repeated system prompts, long documents, and few-shot examples are stored once at the gateway layer and reused across OpenAI, Anthropic, Google, and self-hosted models. Instead of paying full input token costs on every request, your application sends a cache reference, and the gateway rehydrates the context before forwarding it downstream. Why does that matter? Teams running high-volume agents and retrieval pipelines typically see input token spend fall 40 to 70 percent, with median latency dropping by several hundred milliseconds. Caches are scoped per project, encrypted at rest, and invalidated automatically when a prompt template changes. Enable it with a single header, and see the docs for TTL tuning and per-route controls.
salida 1593 tok latencia 19.1 s
Obediencia a las restricciones (presupuesto de palabras, lista de palabras prohibidas, la única pregunta), huella de estilo, y control de la longitud.
Cambia entre ellos con una línea
Ambos IDs están en cada pestaña a continuación — el par de líneas resaltadas es la única edición. Mismo endpoint, misma clave, misma estructura de solicitud.
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",
# model="claude-opus-5", # descomenta esta línea, comenta la de arriba
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",
// model: "claude-opus-5", // descomenta esta línea, comenta la de arriba
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",
# "model": "claude-opus-5", # descomenta esta línea, comenta la de arriba
"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",
// Model: "claude-opus-5", // descomenta esta línea, comenta la de arriba
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")
// .model("claude-opus-5") // descomenta esta línea, comenta la de arriba
.addUserMessage("Summarize this diff")
.reasoningEffort(ReasoningEffort.MEDIUM)
.build());
System.out.println(resp.choices().get(0).message().content().orElse(""));Preguntas frecuentes
¿Cuál es más barato, Claude Fable 5 o Claude Opus 5?
Claude Opus 5 es más barato en entrada / 1m tokens ($5 vs $10, con una diferencia de 2.0×). Otras filas pueden indicar lo contrario — la tabla anterior muestra la ficha completa, y el costo real depende de su combinación.
¿Puedo hacer pruebas A/B de Claude Fable 5 frente a Claude Opus 5 sin dos integraciones?
Sí. Ambos se sirven a través del mismo endpoint compatible con OpenAI con una clave API — el cambio es una modificación de una línea en la cadena del modelo, por lo que puede enrutar una fracción del tráfico a cada uno y comparar las facturas directamente.
¿Admiten Claude Fable 5 y Claude Opus 5 caché de prompts?
Sí — ambos cobran las lecturas en caché por debajo de su tarifa de entrada, por lo que las cargas de trabajo con prefijo caliente cuestan menos de lo que sugieren las tarifas de lista. Las filas exactas de lectura en caché están en la tabla de precios de arriba.