Pricing per million tokens, context window, capabilities — pulled from each provider's public docs. All 2 are available via the same AIgateway OpenAI-compatible endpoint; flip the model string to switch.
Claude Fable 5 is Anthropic's most capable widely released model, built for the most demanding reasoning and long-horizon agentic work. Adaptive thinking is always on, and the model supports a 1M token context window with up to 128k output tokens per request.
GPT-5.5 pro uses OpenAI's Responses API with built-in tools, improved reasoning, and stateful context management.
from openai import OpenAI
client = OpenAI(
base_url="https://api.aigateway.sh/v1",
api_key="sk-aig-...",
)
# Claude Fable 5
client.chat.completions.create(
model="anthropic/claude-fable-5",
messages=[{"role":"user","content":"hello"}],
)
# GPT-5.5 Pro
client.chat.completions.create(
model="openai/gpt-5.5-pro",
messages=[{"role":"user","content":"hello"}],
)