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

Annotations already declare readOnlyHint and openWorldHint, and the description adds real context on top: a cap of 20 results per call, most-relevant-first ordering, and the fact that failed calls are not billed. It doesn't discuss rate limiting or how results are ranked beyond 'most relevant', but the paid-call and result-size disclosures are exactly the kind of behavior an agent needs.

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 definition is short and front-loads the resource and returned fields before routing and pricing. The 'Choose this tool for:' sentence is near-verbatim duplication of the opening and could be cut, which keeps it from a 5.

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 read-only two-parameter search tool with an output schema and 100% parameter coverage, everything needed to call it correctly is present: query constraints, result cap, ordering, and cost. Return-value detail is covered by the output schema, so its absence from prose is not a gap.

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 both parameters (q and max) are already documented in the schema, including the 2-100 character range and the 1-20 bound with default 5. The description's 'Up to 20 projects per call' reinforces the max bound but adds no syntax or format meaning beyond 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 and resource ('NIH RePORTER funded research projects matching a text search') and enumerates the returned fields (project number, title, fiscal year, award amount, lead organization, PIs). It explicitly separates itself from the two named siblings, so an agent can pick it without opening the schema.

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?

It names close alternatives (health_daily_med_label_spl, health_drugbank_interaction) with a short scope note for each, which makes disambiguation straightforward. The 'Choose this tool for:' line, however, only restates the opening sentence rather than giving an explicit when-not-to-use condition.

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