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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description still adds meaningful context beyond them: the OAuth requirement, an explicit scope boundary ("no writes and no other account access"), and the fact that freshness/source metadata accompanies the data.

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 short sentences with no filler; the access requirement is front-loaded, followed by scope, then output conventions. Every clause carries information an agent would otherwise have to guess.

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 no output schema, the description does the right thing by noting that data comes with source/freshness metadata and by fixing the units and direction convention. It stops short of indicating what a vessel record actually contains (name, draft, beam, clearance values), which is the remaining gap for a zero-param read.

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?

The tool takes zero parameters, so the baseline is 4 and the schema (vacuously 100% covered) carries no burden. The units and FROM-direction conventions describe output rather than inputs, so they do not raise or lower this score.

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 verb (reads) and a specific, ownership-scoped resource ("your saved vessel and route clearance settings"), which distinguishes it from the public-object sibling get_boat. However, it never names get_boat or any other sibling explicitly, so the differentiation must be inferred from the possessive phrasing.

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 real prerequisite ("Requires OAuth login to your Gillby account") and implies the use case via "your saved vessel," but it never states when to prefer this over get_boat or how it relates to get_my_settings/get_my_trip. Usage is implied rather than instructed.

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