---
title: "Claude / Anthropic Model Catalog"
aliases: [claude-models, anthropic-models, opus-sonnet-haiku]
tags: [claude, anthropic, models, llm, ai]
sources: [knowledge cutoff Aug 2025 + Claude Code system context]
created: 2026-04-17
updated: 2026-04-17
---

## Model Families

| Family | Tier | Best for |
|--------|------|----------|
| Opus 4.x | Most capable | Complex reasoning, architecture, long-form writing |
| Sonnet 4.x | Balanced | Coding, agentic tasks, daily work — best cost/performance |
| Haiku 4.x | Fast & cheap | Logging, classification, summaries, bulk operations |

## Current Model IDs (Claude 4.x)

| Model | ID | Context | Notes |
|-------|----|---------|-------|
| **Opus 4.7** | `claude-opus-4-7` | 200K | Most powerful. Fast Mode available (same model, faster output) |
| **Sonnet 4.6** | `claude-sonnet-4-6` | 200K | Default in Claude Code. Best everyday coding model |
| **Haiku 4.5** | `claude-haiku-4-5-20251001` | 200K | Use for logging/notes in Obsidian vault (per CLAUDE.md) |

## When to Use Each Model

**Opus** — multi-step reasoning, large refactors, security reviews, novel architecture decisions

**Sonnet** — default for all coding tasks; Claude Code uses this; agentic pipelines, tool use, RAG

**Haiku** — Obsidian session logging, bulk text processing, classification, any "just write text" task; cheapest

## Claude Code Context

- Claude Code CLI currently runs on **Sonnet 4.6** by default
- `/fast` toggles Fast Mode on Opus 4.6 (faster output, same quality)
- Memory compiler `flush.py` / `compile.py` should use Sonnet; **Obsidian logging uses Haiku** (per vault CLAUDE.md)
- Agent SDK: pass model ID in `ClaudeAgentOptions` → `model` field

## API Usage

```python
from anthropic import Anthropic

client = Anthropic()
response = client.messages.create(
    model="claude-sonnet-4-6",   # or opus-4-7, haiku-4-5-20251001
    max_tokens=1024,
    messages=[{"role": "user", "content": "Hello"}]
)
```

## Key Takeaways

- Default to **Sonnet 4.6** for agentic/coding work — best balance
- Use **Haiku** for any high-volume or low-stakes generation (logging, summaries) to cut costs
- Use **Opus** only when the task genuinely requires maximum reasoning
- Model IDs include version suffix — always use full ID in code to avoid silent upgrades
- All 4.x models support 200K context window

## Related

- [[wiki/agent-sdk/overview|Agent SDK Overview]] — how to pass model to ClaudeAgentOptions
- [[wiki/claude-code/overview|Claude Code Overview]] — default model and Fast Mode
- [[wiki/llm-models/openai-model-catalog|OpenAI Model Catalog]] — comparison reference
