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

Annotations already establish read-only, open-world, and idempotent behavior. The description adds useful behavioral context by enumerating the returned metadata fields (title, authors, MeSH terms, DOI, citation count, etc.) and clarifying accepted identifier types. This 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 front-loaded with the core purpose and then gives identifier guidance, return fields, and usage context. The returned-field list is long but informative. It is slightly verbose, but every sentence earns its place.

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 100% schema coverage, rich annotations, and an output schema present, the description provides everything an agent needs to call the tool correctly: what it does, which IDs to use, when to use it, and what it returns. No critical operational gap remains.

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 coverage is 100%, so the baseline is 3. The description adds real value by explaining identifier semantics: PMID for MEDLINE articles, PMC ID for PubMed Central, and other source-specific IDs. This helps an agent map the right ID type to the right source without opening 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?

The description states a specific verb ('Retrieve'), a specific resource ('full bibliographic details for a specific biomedical article from Europe PMC'), and the unique identifier basis. It also distinguishes itself from search by saying 'Use this after a search to retrieve the full record for a specific paper.' This makes the tool's role clear relative to sibling tools.

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 clear context: use it after a search to get the full record for a specific paper, and it explains which identifier types are appropriate. It does not explicitly mention sibling alternatives like europepmc.literature.citations or europepmc.literature.references for related use cases, so it stops short of full when-not-to-use guidance.

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