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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint=false, so safety is covered; the description goes further by disclosing the data sources, the default sort order (newest award first), and the exact fields returned (title, funder, holder, investigators, amount, funded period, scheme, link). These are behavioral traits the annotations cannot convey.

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 dense sentences, front-loaded with the trigger before the routing exclusion and the filter list. Nearly every clause earns its place, though the second sentence packs sources, sort order, return fields and filter modes into one long run-on that could be slightly tightened.

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 an 8-parameter, no-required-args listing tool with no output schema, the description supplies the missing return-value detail (enumerated fields), the ordering guarantee, the source coverage, and the filter model. Nothing an agent needs to select or invoke it correctly is absent.

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, but the description adds meaning beyond the schema by tying the entity filter to a sibling ('type:key, as find_entities gives') so the agent knows where to obtain a valid key, and by framing the filters as narrowing dimensions (entity named in title, funder/holder key, title words, award date). It does not restate format details like the cursor's page-continuation contract.

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 and resource (lists research grants) plus scope (aging-relevant grants from NIH, CORDIS, UKRI, Wellcome, newest first). It also names the sibling it is not — 'for company financings use list_news' — so an agent can distinguish it from other list_* tools without opening schemas.

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?

Opens with an explicit trigger ('when the user asks who funds work on a target, a drug, a process or a lab, how much and since when') and closes with an exclusion plus the correct alternative ('Other funders and private money are not here; for company financings use list_news'). Both when-to-use and when-not-to-use are covered.

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