Claude Model Family

The three tiers

Tier	Tagline	Use for
Opus	Most capable	Hard reasoning, agents, complex code, long-horizon planning
Sonnet	Balanced	Production workloads, RAG, most agent loops, day-to-day API use
Haiku	Fastest & cheapest	Classification, routing, high-volume tasks, edge latency-sensitive flows

Current model IDs (Claude 4 family)

• Opus 4.7 — claude-opus-4-7
• Sonnet 4.6 — claude-sonnet-4-6
• Haiku 4.5 — claude-haiku-4-5-20251001

Always pin the model ID in production. When migrating, run evals on the new model before flipping traffic.

Picking a model

A pragmatic decision tree:

1. Is this a high-volume routing/classification step? → Haiku.
2. Does it need deep reasoning, tool use across many turns, or long-horizon planning? → Opus.
3. Everything else → Sonnet (default for most production agents).

For agent loops the standard pattern is:

• Haiku for cheap subagents and routers.
• Sonnet for the main worker.
• Opus for the orchestrator on hard problems.

Tradeoffs to internalize

• Capability ↑ → cost & latency ↑.
• A bigger model with no prompt caching can be slower and pricier than a smaller model with caching.
• Extended thinking trades latency for accuracy on hard problems — don't enable it for trivial calls.

See also

• messages-api — how to specify model in requests
• prompt-caching — cost levers
• extended-thinking — when to enable thinking