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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile needs no restating. The description adds genuine behavioral context the annotations cannot: tide data exists only for coastal ports, freshwater input returns moon phase plus bestWindows instead, and 'mes' returns the entire published month. It does not cover what happens when no location parameter is supplied, which would have earned a 5.

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 sentences, front-loaded with the output inventory before the usage triggers, and the freshwater caveat is placed last as a genuine edge case. Slightly dense in the middle sentence where date and range guidance are packed together, but no filler sentences.

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?

Seven optional parameters, no output schema, and no required fields make this a tool whose failure modes matter, and the description covers the two big ones: coastal-only tide data and freshwater fallback behavior. It also names the returned fields, compensating for the absent output schema. The remaining gap is what occurs when the agent passes no location hint at all.

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 baseline is 3 and every parameter is already documented with examples. The description adds some meaning beyond the schema, notably that portSlug is more reliable than free-text city search and that range drives a full-month publication, but most of its parameter remarks (date formats, default today) restate the schema.

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 statement ('Condições de pesca de um dia') and enumerates the exact payload: tide table, moon phase, best time windows, water temperature and weather. No sibling tool (get_location, get_species, find_guides, search_destinations) overlaps with fishing conditions, so the agent can route unambiguously.

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?

Explicit trigger conditions are given: ask about tide, moon, best fishing time, or whether the day is good. Defaults and extensions are spelled out (today by default; date for tomorrow/weekday/date; range for week or month). It stops short of naming a when-not-to-use case or an alternative tool, but the trigger list is concrete enough that little is left to inference.

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