Claude Fable 5 1 API

A high-capability Opus model for complex, long-running software engineering and agent tasks. Compared with Opus 4.6, it emphasizes precise instruction following, higher-resolution vision, sustained execution, and self-verification for large codebases, difficult debugging, document analysis, and multi-step tool use.

A thinking-oriented configuration variant built on Claude Opus 4.7, suited to deeper analysis, complex planning, and multi-step tool execution. It is not a separate model family; higher thinking effort generally increases latency and output usage, so use standard Opus 4.7 or Sonnet when speed matters.

An earlier Opus model in the Claude 4 family, focused on difficult coding, agents, computer use, deep research, and work with slides and spreadsheets. It fits workflows that require Opus-level capability with 4.5 compatibility; without that constraint, evaluate the newer Opus 4.6 or 4.7 first.

A premium model for complex agentic coding and enterprise knowledge work, emphasizing long-horizon planning, sustained execution, self-checking, and reliable delivery. With a million-token context window, it is suited to large codebases, complex documents, and multi-step projects that need limited human oversight.