Update claude-api skill: Claude Fable 5 and Claude Mythos 5 (#1294)

- Add Claude Fable 5 and Claude Mythos 5 to the model tables with pricing,
  context window, and model-selection guidance
- Document Fable-specific API behavior: always-on adaptive thinking (explicit
  disabled returns 400), protected-thinking display and replay rules, new
  tokenizer (~30% more tokens), refusal stop reason with server-side fallbacks
  and SDK fallback middleware, 30-day data-retention requirement
- Add the full Migrating to Claude Fable 5 guide section and checklist,
  including the Mythos Preview migration path
- Refresh skill trigger description, effort/compaction/task-budget notes,
  caching minimums, structured-output and dynamic-filtering support tables
This commit is contained in:
Lance Martin
2026-06-09 10:34:55 -07:00
committed by GitHub
parent c30d329f58
commit 5d25128289
13 changed files with 306 additions and 40 deletions
@@ -171,7 +171,7 @@ Web search and web fetch let Claude search the web and retrieve page content. Th
]
```
### Dynamic Filtering (Opus 4.8 / Opus 4.7 / Opus 4.6 / Sonnet 4.6)
### Dynamic Filtering (Fable 5 / Opus 4.8 / Opus 4.7 / Opus 4.6 / Sonnet 4.6)
The `web_search_20260209` and `web_fetch_20260209` versions support **dynamic filtering** — Claude writes and executes code to filter search results before they reach the context window, improving accuracy and token efficiency. Dynamic filtering is built into these tool versions and activates automatically; you do not need to separately declare the `code_execution` tool or pass any beta header.
@@ -300,7 +300,7 @@ Two features are available:
- **JSON outputs** (`output_config.format`): Control Claude's response format
- **Strict tool use** (`strict: true`): Guarantee valid tool parameter schemas
**Supported models:** Claude Opus 4.8, Claude Sonnet 4.6, and Claude Haiku 4.5. Legacy models (Claude Opus 4.5, Claude Opus 4.1) also support structured outputs.
**Supported models:** Claude Fable 5, Claude Opus 4.8, Claude Sonnet 4.6, and Claude Haiku 4.5. Legacy models (Claude Opus 4.5, Claude Opus 4.1) also support structured outputs.
> **Recommended:** Use `client.messages.parse()` which automatically validates responses against your schema. When using `messages.create()` directly, use `output_config: {format: {...}}`. The `output_format` convenience parameter is also accepted by some SDK methods (e.g., `.parse()`), but `output_config.format` is the canonical API-level parameter.