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

Annotations already declare readOnlyHint, idempotentHint and non-destructive, so safety is covered. The description adds genuinely non-obvious behavioral context: dates are New Zealand dates, and the data may be stale enough that the funder's own site must be confirmed. That caveat materially changes how an agent should present results.

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 tight sentences, front-loaded with the core filter and ordering, then constraints, then the caveat. No filler and nothing buried.

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?

No output schema exists, yet the description supplies ordering, defaults, time-zone grounding and a data-reliability caveat, which is enough for an agent to call and report correctly. The one gap is the undocumented 'limit' parameter.

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 0%, so the description must carry the parameters. It explains 'days' and clarifies that 'region' is a slug sourced from list_filters (real added meaning), but the bounds it repeats are already in the schema and the 'limit' parameter is never mentioned anywhere.

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 resource (funding rounds), a precise filter (closing date within next N days), and an ordering guarantee (soonest first). The 'closing' framing cleanly separates it from rounds_opening_soon without needing to name it.

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?

Gives concrete operating context: default 30 / max 180 days, soonest-first ordering, and routes the agent to list_filters for valid region slugs. It does not state when to prefer this over rounds_opening_soon or search_funders, so no explicit exclusion is present.

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