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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and closed-world, so safety is covered. The description adds genuinely new behavioural detail that annotations cannot: an exact deterministic sort order (deadline soonest-first with rolling/unknown last, then name, then slug). It does not describe pagination limits or result-count behaviour, which would have completed the picture.

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 tightly packed sentences, front-loaded with purpose and filters before the ordering and hand-off details. Nothing is repeated and every clause carries operational information.

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 a fully documented 9-parameter schema, an output schema, and complete annotations, the description covers the remaining gaps an agent needs: resource scope, sort determinism, and the slug hand-off to opportunity_detail. Nothing required for a correct call 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% and each parameter is already documented with enums, defaults, formats and even the include_rolling/deadline-filter interaction. The description echoes the filter set but adds no syntax, format or edge-case meaning beyond the schema, so the baseline 3 applies.

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 opens with a specific verb and resource ('Find open and upcoming opportunities') and enumerates the filter dimensions (jurisdiction, cause area, region, deadline). It is clearly distinct from the funder-oriented siblings and names opportunity_detail as the natural follow-up, so an agent can route without opening either 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?

'Use the slug of a result with opportunity_detail' gives an explicit next-step routing rule, and 'Results are not ranked against an organization' clarifies this is a catalogue search, not a personalized match. It stops short of stating when *not* to use it (e.g., searching funders), but the resource split is obvious from the sibling names.

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