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

Annotations already cover safety (readOnly, idempotent, non-destructive), but the description adds real behavioral detail: results are sorted soonest-first, days-left is computed in Eastern Time, and listings with missing or placeholder close dates are silently excluded. That last exclusion is a genuine data-quality caveat an agent would otherwise not know.

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 sentences, front-loaded with the core behavior (window, default, ordering, timezone) before the filter-parity and exclusion details. No filler; every clause conveys a distinct constraint.

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 no output schema, the description still conveys the return shape (ordered listings with a days-left field counted in ET), the default window, and the exclusion rule, while annotations cover the safety profile. Nothing needed to call it correctly is missing.

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 description coverage is 100%, so the schema already documents all 9 parameters thoroughly. The description adds only that filters mirror search_grants and reiterates the within_days default; the baseline 3 is appropriate when the schema carries the semantics.

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 (List) and resource (posted Grants.gov opportunities) plus the defining scope: deadline within 1-120 days, default 30, soonest first. This is clearly distinguishable from search_grants, which it names as the filter-compatible sibling.

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 'closing soon' framing and the 1-120 day window make the use case clear, and it explicitly says it accepts the same filters as search_grants, which helps an agent route between the two. It does not state when NOT to use it (e.g., use search_grants for deadline-agnostic search), so it falls short of a 5.

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