anthropics-claude-api/shared/models.md

Claude Model Catalog

Only use exact model IDs listed in this file. Never guess or construct model IDs - incorrect IDs will cause API errors. Use aliases wherever available. For the latest information, WebFetch the Models Overview URL in shared/live-sources.md, or query the Models API directly (see Programmatic Model Discovery below).

Programmatic Model Discovery

For live capability data - context window, max output tokens, feature support (thinking, vision, effort, structured outputs, etc.) - query the Models API instead of relying on the cached tables below. Use this when the user asks "what's the context window for X", "does model X support vision/thinking/effort", "which models support feature Y", or wants to select a model by capability at runtime.

m = client.models.retrieve("claude-opus-4-8")
m.id                 # "claude-opus-4-8"
m.display_name       # "Claude Opus 4.8"
m.max_input_tokens   # context window (int)
m.max_tokens         # max output tokens (int)

# capabilities is an untyped nested dict - bracket access, check ["supported"] at the leaf
caps = m.capabilities
caps["image_input"]["supported"]                       # vision
caps["thinking"]["types"]["adaptive"]["supported"]     # adaptive thinking
caps["effort"]["max"]["supported"]                     # effort: max (also low/medium/high)
caps["structured_outputs"]["supported"]
caps["context_management"]["compact_20260112"]["supported"]

# filter across all models - iterate the page object directly (auto-paginates); do NOT use .data
[m for m in client.models.list()
 if m.capabilities["thinking"]["types"]["adaptive"]["supported"]
 and m.max_input_tokens >= 200_000]

Top-level fields (id, display_name, max_input_tokens, max_tokens) are typed attributes. capabilities is a dict - use bracket access, not attribute access. The API returns the full capability tree for every model with supported: true/false at each leaf, so bracket chains are safe without .get() guards. TypeScript SDK: same method names, also auto-paginates on iteration.

Raw HTTP

curl https://api.anthropic.com/v1/models/claude-opus-4-8 \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01"

{
  "id": "claude-opus-4-8",
  "display_name": "Claude Opus 4.8",
  "max_input_tokens": 1000000,
  "max_tokens": 128000,
  "capabilities": {
    "image_input": {"supported": true},
    "structured_outputs": {"supported": true},
    "thinking": {"supported": true, "types": {"enabled": {"supported": false}, "adaptive": {"supported": true}}},
    "effort": {"supported": true, "low": {"supported": true}, ..., "max": {"supported": true}},
    ...
  }
}

Current Models (recommended)

Friendly Name	Alias (use this)	Full ID	Context	Max Output	Status
Claude Fable 5.1	claude-fable-5-1	-	1M	128K	Active
Claude Mythos 5.1	claude-mythos-5-1	-	1M	128K	Active (Project Glasswing only)
Claude Fable 5	claude-fable-5	-	1M	128K	Active
Claude Mythos 5	claude-mythos-5	-	1M	128K	Active (Project Glasswing only)
Claude Opus 5.5	claude-opus-5-5	-	1M	128K	Active
Claude Opus 5	claude-opus-5	-	1M	128K	Active
Claude Opus 4.8	claude-opus-4-8	-	1M	128K	Active
Claude Opus 4.7	claude-opus-4-7	-	1M	128K	Active
Claude Opus 4.6	claude-opus-4-6	-	1M	128K	Active
Claude Sonnet 5.5	claude-sonnet-5-5	-	1M	128K	Active
Claude Sonnet 5	claude-sonnet-5	-	1M	128K	Active
Claude Sonnet 4.6	claude-sonnet-4-6	-	1M	128K	Active
Claude Haiku 4.5	claude-haiku-4-5	claude-haiku-4-5-20251001	200K	64K	Active

Model Descriptions

• Claude Fable 5.1 - Anthropic's most capable widely released model, for the most demanding reasoning and long-horizon agentic work. Successor to Claude Fable 5 in the same tier at the same per-token price ($10/$50 per MTok; cache reads $0.25/MTok - 0.025x, a quarter of Claude Fable 5's; batch $5/$25); stronger long-running agentic coding, knowledge work with documents/spreadsheets/slides, multistep research, vision, long-context retrieval, and computer use. Same API surface as Claude Fable 5 (thinking always on, no prefill, no sampling params, refusal stop reason, 512-token cache minimum) with three breaking changes: forced tool use (tool_choice any / tool) returns a 400; thinking blocks are bound to the producing model (only Claude Mythos 5.1 can read them - other models drop them); and editing earlier turns invalidates thinking blocks ("preserved thinking"; new accounts created on/after 2026-08-31 get a 400 on edited history on every platform, and enforcement scope is decided per model; the opt-in controls beta is on the Claude API, Claude Platform on AWS, Bedrock, and Vertex - Foundry unconfirmed, shared/platform-availability.md). Adds per-message effort, turn-scoped clear_at system messages, thinking.display: "updates" progress updates, and content provenance. Same tokenizer as Claude Fable 5; 1M context (default), 128K max output. Covered Model: 30-day retention required (ZDR only if expressly authorized by Anthropic) - ZDR orgs get 400 invalid_request_error, as on Claude Fable 5. No Priority Tier; shares the Fable 5.x rate-limit pool. See shared/model-migration.md -> Migrating to Claude Fable 5.1 from Claude Fable 5.
• Claude Fable 5 / Claude Mythos 5 (claude-fable-5 / claude-mythos-5) - the previous Fable / Mythos release: same tier, limits and per-token pricing as Claude Fable 5.1, which adds three breaking API changes over them (see above; cache reads here are $1/MTok rather than Claude Fable 5.1's $0.25); still served and selectable by id. Claude Mythos 5 ran no safety classifiers, so stop_reason: "refusal" does not occur on it. Prefer claude-fable-5-1 for new work.
• Claude Mythos 5.1 - The same model as Claude Fable 5.1 (same capabilities, limits, per-token pricing, API behavior - except it does not run the history-editing check), offered only to approved Project Glasswing customers; successor to Claude Mythos 5 (which itself succeeded the invitation-only claude-mythos-preview). Unlike Claude Mythos 5 it runs safeguards that depend on the access program, so handle stop_reason: "refusal". Not offered on Claude Platform on AWS. Use it only when the org participates in Project Glasswing; otherwise use claude-fable-5-1.
• Claude Opus 5.5 - Successor to Claude Opus 5 in the Opus line for long-running agentic coding and knowledge work, at a lower price ($4 / $20 per MTok; cache reads $0.20). Same 1M context, 128K output, tokenizer, and feature set as Claude Opus 5, with four breaking changes: thinking can't be disabled (effort is the only control, default medium), forced tool_choice 400s, thinking blocks are tied to the model and the conversation, and computer use needs the computer_toolset_20260801 toolset. Broader safety classifiers (bio and reasoning_extraction join cyber). The current Opus and the default model; see shared/model-migration.md -> Migrating to Claude Opus 5.5.
• Claude Opus 5 - For complex agentic coding and enterprise work; a step-change over Claude Opus 4.8, strongest on deep reasoning, agentic and long-horizon work, and test-time compute scaling, at half the cost of Claude Fable 5.1 (Claude Fable 5.1 remains the highest-capability tier). Safety classifiers can return stop_reason: "refusal" - handle it before reading content. A drop-in upgrade at Opus 4.8's pricing ($5/$25 per MTok) with the same feature set. Thinking is on by default (omitting thinking runs adaptive; {type: "adaptive"} is equivalent), and thinking: {type: "disabled"} is available only at effort high or lower - pairing it with xhigh/max returns a 400. Raw thinking tokens are never returned. Full effort ladder through max; 512-token prompt-cache minimum (down from 1024 on Opus 4.8); fast mode on the Claude API only. Elevated cybersecurity safeguards. Separate rate-limit bucket from the combined Opus 4.x pool. 1M context window (default and maximum), 128K max output. See shared/model-migration.md -> Migrating to Claude Opus 5.
• Claude Opus 4.8 - The most capable model in the Opus 4 series - highly autonomous, state-of-the-art on long-horizon agentic work, knowledge work, and memory; clearer, warmer writing. Same API surface as Opus 4.7 (adaptive thinking only; sampling parameters and budget_tokens removed). 1M context window at standard API pricing (no long-context premium). See shared/model-migration.md -> Migrating to Opus 4.8 - a 4.7 -> 4.8 move is a model-ID swap plus prompt re-tuning, no new breaking changes.
• Claude Opus 4.7 - Previous-generation Opus. Highly autonomous; strong on long-horizon agentic work, knowledge work, vision, and memory. Adaptive thinking only; sampling parameters and budget_tokens removed. 1M context window. See shared/model-migration.md -> Migrating to Opus 4.7.
• Claude Opus 4.6 - Older Opus. Supports adaptive thinking (recommended), 128K max output tokens (requires streaming for large outputs). 1M context window.
• Claude Sonnet 5 - The previous Sonnet; near-Opus quality on coding and agentic work. Adaptive thinking on by default (omitting thinking runs adaptive); manual budget_tokens removed; non-default sampling parameters rejected. effort supports low/medium/high/xhigh/max. New tokenizer (~30% more tokens for the same text vs Sonnet 4.6). High-resolution vision (2576px). 1M context window, 128K max output. See shared/model-migration.md -> Migrating to Claude Sonnet 5.
• Claude Sonnet 5.5 - Successor to Claude Sonnet 5 in the Sonnet line, at the same prices ($2 / $10 per MTok; cache reads $0.20). Same tokenizer as Claude Sonnet 5; 1M context, 128K max output. Adaptive thinking on by default; effort default high, with recalibrated levels. Five breaking changes: thinking: {type: "disabled"} returns a 400 (send {type: "between_tools"} at effort high or below to turn thinking off), forced tool_choice 400s, thinking blocks are tied to the model and the conversation, computer use on the Claude API and Google Cloud needs the computer_toolset_20260801 toolset, and the advisor tool rejects Claude Opus 4.8, Claude Opus 4.7, and Claude Sonnet 5 advisors. See shared/model-migration.md -> Migrating to Claude Sonnet 5.5.
• Claude Sonnet 4.6 - Previous-generation Sonnet. Supports adaptive thinking (recommended). 1M context window. 128K max output tokens.
• Claude Haiku 4.5 - Fastest and most cost-effective model for simple tasks.

Legacy Models (still active)

Friendly Name	Alias (use this)	Full ID	Status
Claude Opus 4.5	claude-opus-4-5	claude-opus-4-5-20251101	Active
Claude Opus 4.1	claude-opus-4-1	claude-opus-4-1-20250805	Deprecated (retires 2026-08-05 - migrate to claude-opus-5-5)
Claude Sonnet 4.5	claude-sonnet-4-5	claude-sonnet-4-5-20250929	Active

Deprecated Models (retiring soon)

Friendly Name	Alias (use this)	Full ID	Status	Retires
Claude Sonnet 4	claude-sonnet-4-0	claude-sonnet-4-20250514	Deprecated	TBD
Claude Opus 4	claude-opus-4-0	claude-opus-4-20250514	Deprecated	TBD
Claude Haiku 3	-	claude-3-haiku-20240307	Deprecated	Apr 19, 2026

Retired Models (no longer available)

Friendly Name	Full ID	Retired
Claude Sonnet 3.7	claude-3-7-sonnet-20250219	Feb 19, 2026
Claude Haiku 3.5	claude-3-5-haiku-20241022	Feb 19, 2026
Claude Opus 3	claude-3-opus-20240229	Jan 5, 2026
Claude Sonnet 3.5	claude-3-5-sonnet-20241022	Oct 28, 2025
Claude Sonnet 3.5	claude-3-5-sonnet-20240620	Oct 28, 2025
Claude Sonnet 3	claude-3-sonnet-20240229	Jul 21, 2025
Claude 2.1	claude-2.1	Jul 21, 2025
Claude 2.0	claude-2.0	Jul 21, 2025

Resolving User Requests

When a user asks for a model by name, use this table to find the correct model ID:

User says...	Use this model ID
"fable", "most capable model"	claude-fable-5-1
"most powerful"	claude-fable-5-1
"mythos", "mythos 5.1"	claude-mythos-5-1 (Project Glasswing participants only; otherwise use claude-fable-5-1)
"fable 5", "mythos 5" (previous version)	claude-fable-5 / claude-mythos-5 (still served; prefer claude-fable-5-1 for new work)
"mythos preview"	claude-mythos-5-1 (successor to claude-mythos-preview - see migration guide)
"opus"	claude-opus-5-5
"opus 5"	claude-opus-5
"opus 5.5"	claude-opus-5-5
"opus 4.8"	claude-opus-4-8
"opus 4.7"	claude-opus-4-7
"opus 4.6"	claude-opus-4-6
"opus 4.5"	claude-opus-4-5
"opus 4.1"	claude-opus-4-1 (deprecated, retires 2026-08-05 - suggest claude-opus-5-5)
"opus 4", "opus 4.0"	claude-opus-4-0 (deprecated - suggest claude-opus-5-5)
"sonnet", "balanced"	claude-sonnet-5-5
"sonnet 5"	claude-sonnet-5
"sonnet 5.5"	claude-sonnet-5-5
"cheapest sonnet", "newest sonnet", "latest sonnet" (any attribute phrasing)	claude-sonnet-5-5
"sonnet 4.6"	claude-sonnet-4-6
"sonnet 4.5"	claude-sonnet-4-5
"sonnet 4", "sonnet 4.0"	claude-sonnet-4-0 (deprecated - suggest claude-sonnet-5-5)
"sonnet 3.7"	Retired - suggest claude-sonnet-5-5
"sonnet 3.5"	Retired - suggest claude-sonnet-5-5
"haiku", "fast", "cheap"	claude-haiku-4-5
"haiku 4.5"	claude-haiku-4-5
"haiku 3.5"	Retired - suggest claude-haiku-4-5
"haiku 3"	Deprecated - suggest claude-haiku-4-5