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

Annotations already cover read-only, idempotent, and closed-world semantics, so the bar is lower. The description adds genuine behavioral context beyond them: the sort order, the New Zealand date basis, and a caution that dates should be verified on the funder's own site before relying on them — a real data-reliability caveat.

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?

Four tight sentences with the scope, defaults, filter source, and caveat ordered sensibly and front-loaded. No filler, though the date-range bounds duplicate schema data at some cost to density.

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 listing tool with no output schema, the description supplies the sort order, region-filter provenance, and freshness caveat an agent needs. Only the unmentioned limit parameter and the absence of any sibling routing leave a minor 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 description coverage is 0%, so the description must carry the load. It explains region as a slug sourced from list_filters — genuinely non-obvious and valuable — but the 60/180 values it repeats for days are already in the schema (no credit), and the limit parameter is never mentioned at all.

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 and scope: funding rounds whose opening date falls within the next N days, returned soonest first. The 'opening' framing inherently distinguishes it from the sibling rounds_closing_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?

'Useful for planning applications ahead of time' implies the use case but gives no explicit when-to-use vs when-not, and never names rounds_closing_soon as the alternative for the opposite time window. The agent must infer the routing decision from the tool name alone.

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