Claude Opus 5 Is Now Available in Cosmic

Anthropic launched Claude Opus 5 today, and it is available in Cosmic right now. Select it from the model dropdown in your agent or AI settings, or pass claude-opus-5 in the AI text generation API.

What is Claude Opus 5?

Claude Opus 5 is Anthropic's most capable model to date. It sets new state-of-the-art benchmarks on coding, knowledge work, and long-running agent tasks, while matching the intelligence of Claude Fable 5 at roughly half the cost.

Key capabilities verified from the Anthropic announcement:

• State-of-the-art on coding and knowledge work (Frontier-Bench, GDPval-AA)
• Built for long-running agents: #1 on Zapier's AutomationBench end-to-end, ARC-AGI 3 score 3x the next-best model
• Judgment and self-verification: verifies its own work, catches errors during planning, pushes back on bad designs
• Most aligned model to date: 2.3 on misaligned behavior, lowest of recent Anthropic releases
• Same price as Opus 4.8: $5/M input tokens, $25/M output tokens, so you get more capability at the same cost
• Fast mode available: ~2.5x speed increase for latency-sensitive workflows

Use Claude Opus 5 in the Dashboard

Open any Agent in your Cosmic dashboard, go to the model settings, and select Claude Opus 5 from the dropdown. No additional configuration needed. The model is available on all plans.

Use Claude Opus 5 via the API and SDK

Pass claude-opus-5 as the model parameter in the Cosmic AI text generation API:

import { createBucketClient } from '@cosmicjs/sdk';

const cosmic = createBucketClient({
  bucketSlug: 'YOUR_BUCKET_SLUG',
  readKey: 'YOUR_READ_KEY',
  writeKey: 'YOUR_WRITE_KEY'
});

// Generate text with Claude Opus 5
const result = await cosmic.ai.generateText({
  model: 'claude-opus-5',
  prompt: 'Write a product description for our new headless CMS feature',
  max_tokens: 1024
});

console.log(result.text);

Streaming responses

For long-form content generation or agent workflows, use streaming to get results as they arrive:

const stream = await cosmic.ai.generateText({
  model: 'claude-opus-5',
  prompt: 'Write a detailed technical guide on headless CMS architecture',
  stream: true
});

for await (const chunk of stream as TextStreamingResponse) {
  process.stdout.write(chunk.text);
}

Full API reference: AI Text Generation · Available Models

Why Opus 5 Matters for Agent Teams

If you have been following the agent-team pattern, Opus 5 is the right model for your orchestrator role. Its self-verification and judgment capabilities map directly to the human-in-the-loop coordination layer: an Opus 5 orchestrator can verify agent outputs, catch errors before they reach review, and push back on off-brief content without a human having to catch every mistake.

For content agents, code agents, and multi-step workflows, Opus 5's strength on long-running tasks means fewer dropped threads and more reliable end-to-end completions.

Cosmic Is Model-Agnostic

Cosmic supports Claude, Gemini, GPT, Kimi, and other leading models through the same AI text generation API. You choose the model that fits the task. Swap claude-opus-5 for kimi-k3 or any other supported model string without changing your integration.

See the full list of available models.