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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=true, and openWorldHint=true, so the write/safety profile is covered structurally. The description adds genuinely useful context beyond that (account + consent requirement, partial-update behavior, return of source/freshness metadata), but given destructiveHint=true it never explains what could be destroyed or whether changes are reversible, leaving the highest-risk trait unexplained.

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 compact sentences with the purpose front-loaded, then constraints, then units and return info; no filler. The unit line is dense but earns its place given the undefined schema.

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 high-complexity nested settings object, the description covers purpose, consent prerequisite, units, and return metadata, and annotations carry the safety profile. It still omits semantics for the many nested fields and any explanation of the destructive hint, so it is adequate rather than complete.

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% and the single body parameter contains many nested, undocumented fields, so the description must carry the load. It partially compensates by defining units (ft, kt, s, F, mi) and direction convention (FROM) for the numeric fields, but leaves the semantics of most nested properties (alerts, homeSpotIds, view/theme, etc.) entirely undocumented.

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?

It names a specific verb and resource ('Update ... vessel or preference fields') and signals partial-update semantics ('only specified ... fields'), which is clearer than a bare 'Update settings'. It does not explicitly distinguish itself from the nearby siblings update_my_notification_settings, update_my_place, or update_my_trip, so the agent must infer the split by resource name.

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?

It gives a prerequisite condition ('requires your Gillby account and explicit account consent') and implies patch-style partial updates. However it never states when to prefer this tool over get_my_settings for reading or over update_my_notification_settings/update_my_place for the adjacent settings surfaces.

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