Reasoning

Reasoning models can "think" before responding, producing higher-quality answers for complex tasks like coding, math, and multi-step analysis. AI Gateway supports reasoning across multiple providers, including OpenAI, Anthropic, Google, Vertex AI, and Amazon Bedrock. When you use the AI SDK, each provider's native reasoning configuration is passed through providerOptions, and the AI SDK normalizes the output into a consistent format so you can switch providers without rewriting your code.

Enable reasoning with the AI SDK and AI Gateway in a few lines:

import { streamText } from 'ai';
 
const result = streamText({
  model: 'openai/gpt-5',
  prompt: 'Explain the Monty Hall problem step by step.',
  providerOptions: {
    openai: {
      reasoningEffort: 'high',
      reasoningSummary: 'detailed',
    },
  },
});
 
for await (const part of result.fullStream) {
  if (part.type === 'reasoning-delta') {
    process.stdout.write(part.text);
  } else if (part.type === 'text-delta') {
    process.stdout.write(part.text);
  }
}

• Reasoning vs. reasoning text: A model can reason internally without producing visible thinking or reasoning text in the response. Whether reasoning text is returned depends on the model and provider configuration.
• Reasoning token usage: Some providers report reasoning tokens separately in usage metrics (e.g., OpenAI includes reasoning_tokens in completion_tokens_details), but not all do. Anthropic counts thinking tokens as output tokens with no separate breakdown.
• Streaming reasoning to the UI: If you use useChat from the AI SDK, reasoning text is streamed to the client by default. You can disable this with the sendReasoning option. See the AI SDK useChat transport docs for details.

Models like anthropic/claude-opus-4.6 are available through multiple providers (Anthropic, Amazon Bedrock, Google Vertex). When you combine reasoning with provider routing, AI Gateway routes to the first available provider.

Each provider has its own reasoning configuration format. Set the provider-specific options in providerOptions, and the provider that handles the request uses its matching entry:

import { streamText } from 'ai';
 
const result = streamText({
  model: 'anthropic/claude-opus-4.6',
  prompt: 'Prove that there are infinitely many primes.',
  providerOptions: {
    anthropic: {
      thinking: { type: 'adaptive' },
    },
    bedrock: {
      reasoningConfig: { type: 'adaptive' },
    },
  },
});