Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds a scope boundary ('Bibliographic facts only'), which usefully tells the agent not to expect full text or abstracts, but says nothing about latency, rate limits, or how the best-match search ranks candidates. With annotations carrying the behavioral load, a 3 is appropriate.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

A single front-loaded sentence covering both modes and the return payload, with a short scope qualifier. Dense but every clause earns its place; the only minor cost is the long comma-separated field list, which could have been summarized.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

No output schema exists, so the description's field enumeration usefully substitutes for return-value documentation. For a simple read-only lookup with no required parameters, the only real gap is the interaction between doi and query and the behavior of a failed best-match search.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents doi, limit, and query with examples and bounds. The description adds no syntax, format, or precedence rules (e.g. what happens if both doi and query are supplied), so it does not go beyond structured data. Baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States specific verb+resource ('Scholarly metadata by DOI') and explicitly covers the second mode ('best-match search by citation text'), then enumerates exactly what is returned (title, authors, journal, year, publisher, citation count, licence links, URL). No sibling overlaps with this resource, so differentiation is not needed, but the dual mode is unambiguous.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The two operating modes are described, implying 'use doi when known, query otherwise', and the schema param descriptions make the condition explicit ('when no DOI is known'). However, the description itself never states when to prefer one mode, nor any exclusions or fallback behavior if a best-match search finds nothing.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.