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

Annotations already cover readOnly, idempotent, openWorld, and non-destructive behavior. The description adds pricing/rate-limit context ('A few free samples a day, then $0.002 USDC per call via x402'), which is genuinely useful behavioral information beyond annotations. However, it doesn't disclose failure modes for invalid IDs or output format details. With annotations handling safety, a 3 is reasonable.

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 concise sentences front-loading the return fields and input format, then pricing. No wasted words, though the pricing sentence could be seen as slightly tangential to core function.

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 format details are not needed. The description covers input format, output fields, and pricing. It lacks workflow guidance (e.g., get IDs from search) but is otherwise complete for a simple lookup tool.

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%, and the single parameter is documented as 'PMIDs, comma separated'. The description confirms the comma-separated format, reinforcing the schema. For a single well-documented parameter, this is sufficient. Baseline 4 for 0-1 params with high coverage.

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+resource: returns article metadata (title, authors, journal, date, DOI) for given PubMed IDs. Distinguishes itself from sibling pubmed__search by being an ID-based lookup rather than a search. It doesn't explicitly name siblings, but the input shape (comma-separated IDs) makes its role 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?

No guidance on when to use this versus pubmed__search or pubmed__pmc-search. The pricing note implies it's for metadata retrieval, but it doesn't say to call search first to obtain IDs. An agent must infer the workflow.

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