Claude Architect · Lesson

The Claude Model Family

Choosing the right model for cost, speed and capability.

Meet the Model Family

Every Claude API request begins with one decision: which model? That single field sets your cost, your latency, and your intelligence ceiling for the whole call.

The current family spans three tiers:

Opus — the most capable, for the hardest, long-horizon work.
Sonnet — the best balance of speed and intelligence.
Haiku — the fastest and cheapest, for simple high-volume tasks.

As a Claude Certified Architect, picking the right tier per workload is a core skill. Let's build the decision framework.

The model field is just a string

You select a model by passing its model ID as a string. The request also keeps no state — the model is stateless, so you send the full message history on every turn.

The exact ID strings matter. A typo (for example claude-sonnet-4.6 instead of claude-sonnet-4-6) returns a 404 not_found_error, not a silent fallback.

import anthropic

client = anthropic.Anthropic()

response = client.messages.create(
    model="claude-opus-4-8",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Hello, Claude"}],
)
print(response.content[0].text)

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