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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description still adds a genuinely non-obvious behavioral fact: abstracts are excluded and the agent should follow pubmed_url to read them. That is real value beyond the structured fields, though pagination/error behavior is unaddressed.

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?

Two short sentences, front-loaded with the return payload and followed by the one caveat that matters. Nothing is redundant or padding.

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?

With an output schema present, return structure needn't be explained, yet the description still summarizes it usefully. Combined with the abstract caveat, an agent has enough to call this correctly; only sibling routing and parameter format are thin.

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 0%, so only the regex pattern documents the single pmid argument. The description partly compensates by framing pmid as a PubMed ID, but adds no format, length, or validity detail beyond that. Marginal value over the schema.

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 a specific verb and resource ('Citation metadata for a PubMed ID') and enumerates the returned fields (title, journal, year, authors, DOI, design), so an agent knows exactly what it gets. It does not explicitly contrast itself with siblings like lookup_eu_medicine or search_evidence_library, but the PubMed-specific scope makes the distinction reasonably clear.

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 description gives no when-to-use guidance or routing versus the sibling lookup/search tools. The only constraint offered is negative scope ('Abstracts are not returned'), which is a limit, not usage guidance. An agent must infer that this is the single-record citation fetch.

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