You are building a structured data extraction system using Claude.

The dependency must be enforced by orchestration rather than left to probabilistic tool selection. Anthropic documents that tool_choice: {"type": "tool", "name": "..."} forces Claude to invoke the specified tool. By contrast, auto allows Claude to decide whether and which tool to call, while any requires some tool but does not force a particular one. ( https://platform.claude.com/docs/en/agents-and-tools/tool-use/define-tools )

Option A therefore establishes a deterministic two-stage workflow. The first API turn forces extract_metadata , producing the DOI and other structured paper details. The application validates and stores that result. A subsequent turn then exposes or permits verify_doi and lookup_citations , passing the extracted DOI as explicit state. This design converts an implicit tool dependency into an application-controlled execution graph.

Option B is incorrect because array order is not a documented precedence mechanism and cannot guarantee selection. Option C forces extract_metadata on every call, including turns where enrichment should occur, potentially creating an infinite or non-progressing workflow. Option D guarantees only that one available tool is called; Claude could still select lookup_citations before the DOI exists.

For stronger input integrity, the tools can also use strict schemas so their arguments conform to the declared JSON Schema. The sequencing requirement, however, remains the responsibility of the orchestration layer.

Official references/topics: Tool Choice; Forced Tool Invocation; Multi-Turn Tool Orchestration; Tool Dependency Management.