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

Annotations already cover read-only, idempotent, non-destructive and closed-world, so the bar is lower. The description nonetheless adds real business behavior beyond them: what each result carries (fish per place, distance, registered iscabox guides, piracema closure on the requested dates) and the fallback that iscabox staff will source a guide when none is registered.

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: the first carries purpose and filters, the second carries return shape plus the no-guide fallback, with nothing decorative. The first sentence is densely packed with parentheticals, but nothing is redundant.

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 12 optional parameters and no output schema, the description does the work of describing the result fields and the pagePath/requestUrl artifacts, which is the main gap a schema alone would leave. It lacks only edge-case behavior (empty results, how lat/lng interacts with near, how limit truncates ranking).

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 every parameter including lat/lng, max_km, kind and the date pair is already documented in the schema. The description adds only the framing that date_start drives piracema/availability checks and that results are proximity-filtered, which is marginal over the schema's own wording. 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?

States the resource (fishing destinations in Brazil: rivers, reservoirs, lakes, coast) and the three retrieval axes (fish, region, near-city) in one front-loaded clause. It also distinguishes itself from find_guides and request_booking by naming them as downstream consumers of the returned pagePath, so an agent can place it in the workflow without reading the 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?

The filter axes and the downstream handoff (pagePath for find_guides and request_booking, requestUrl for the site request) make the intended use clear, and the note that unguided destinations can still receive a request removes a likely hesitation. It stops short of an explicit when-not-to-use rule or a contrast with search_locations, so no full 5.

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