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

Annotations already declare readOnly, openWorld, idempotent, and non-destructive behavior, so the description does not need to repeat these. It adds useful behavioral details such as the query syntax support, sorting options, and that result_type=core includes abstract and citation count, which goes beyond the annotations without contradicting them.

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?

The description is thorough but not bloated; every sentence conveys relevant information about scope, syntax, sorting, and output. It opens with a clear purpose and efficiently packs in details without redundancy. Slightly long, but justified by the tool's complexity.

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, the description is not required to list return fields, yet it does, which is helpful. It covers query syntax, sorting, pagination via schema, and result_type distinctions. It lacks explicit mention of rate limits or authentication, but for a read-only search tool these are not critical gaps.

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 input schema has 100% coverage with detailed descriptions for each parameter, including the query syntax examples and valid enums. The description repeats much of this information but does not add new meaning beyond what the schema provides, so the baseline of 3 is appropriate.

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 clearly states the tool searches the Europe PMC database, lists the source databases (PubMed/MEDLINE, PubMed Central, bioRxiv/medRxiv), and describes the return fields. It is distinct from the sibling tools europepmc.literature.article, citations, and references, which target specific retrieval tasks rather than broad search.

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 clearly frames the tool as a search interface with rich query syntax and sorting options, giving strong context for its use. However, it does not explicitly mention alternatives (e.g., europepmc.literature.article for fetching a known PMID) or state when not to use it, so it falls short of the highest bar.

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