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

Beyond the annotations (readOnly, openWorld, idempotent, non-destructive), the description adds crucial behavioral context: returns 'exact PubMed search counts for up to 10 calendar years' and warns that volume 'can reflect indexing and terminology changes and is not evidence quality or commercial validation.' This manages expectations and prevents misinterpretation of the output.

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 sentences, with the action in the first sentence. All additional sentences are purposeful: one provides usage scenarios, the other describes output limitations. There is no fluff or repetition of schema details.

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?

Despite having no output schema, the description explicitly states the return value ('exact PubMed search counts for up to 10 calendar years') and caveats. Combined with schema descriptions and safety annotations, the tool is fully specified for an agent to invoke and interpret results correctly.

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 already provides 100% coverage with descriptions for all three parameters. The description adds extra meaning by mentioning the 10-year limit, which clarifies the effective range of from_year/to_year. This goes beyond the schema's generic 'first year' and 'last year' descriptions.

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 opens with a specific action and resource: 'Count PubMed publications by year for a biomedical topic.' This clearly distinguishes it from sibling tools like search_pubmed (which retrieves articles) or pubmed_evidence_landscape (which assesses evidence quality). The verb 'count' and the temporal scope are explicit.

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 provides explicit use cases: 'Use for publication momentum, emerging-target activity, or whether a field is accelerating or cooling.' This gives clear context for when to choose this tool. It does not explicitly name alternatives or state when not to use it, hence not a 5.

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