pubmed_pmc_linkage_lookup_by_pmid

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

With no annotations, the description carries the disclosure burden. It signals a non-destructive 'look up', explains the two result groups are deliberately separated, and explicitly says both empty is normal rather than an error. It doesn't mention auth, rate limits, or output pagination, but these are not critical for a simple lookup.

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?

Three compact sentences: purpose, return groups with inline clarification, and empty-result handling. No filler; the important disambiguation is front-loaded.

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?

For a one-parameter lookup with no output schema, the description covers the main result groups and tells the agent that empty results are valid. It stays short of specifying exact response fields or parameter formatting, but the core invocation semantics are present.

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?

The only parameter, `pmid`, is self-explanatory and the description reinforces it as the article identifier. However, schema_description_coverage is 0%, and the text gives no format/example (e.g., numeric string) or constraints, so it only partially compensates.

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?

The description uses a specific verb ('look up') and resource ('PubMed Central linkages'), then disambiguates the meaning with two named return groups ('own_pmc_fulltext', 'cited_by_pmc_articles'). This makes it clearly distinct from sibling search/summary tools even without naming them.

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 usage is implied by the output description: an agent would call this when it needs PMC full-text availability and citing articles for a PMID. But it never states when to choose this over pubmed_related_article_search_by_pmid or pubmed_paper_summary_lookup_by_pmids, nor provides exclusions.

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