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 is covered. The description adds genuine value by disclosing the information boundary (no deck plans, cabins, prices, availability) and the field set a caller can expect.

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: purpose plus returned fields first, then usage trigger and exclusions. No filler, and the most decision-relevant information is front-loaded.

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 correctly compensates by listing the fields returned and the data explicitly out of scope. It omits any note on result size, caching, or handling of ambiguous ship names, but nothing needed to invoke the tool correctly 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%, so all four parameters (ship, handle, language, cruise_line) are already documented, including the handle's session-memory role and the language enum. The description adds no parameter-level detail 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?

States a specific verb and resource ('Returns the profile of a cruise ship') and enumerates the returned fields: cruise line, year built, size, passengers, crew, consulting description. The sibling 'cruise_line_profile' is not named, though the ship-vs-line distinction is inferable from the resource noun.

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?

Gives explicit triggers ('when the user asks what a ship is like or wants to compare ships') and a clear negative scope ('does NOT return deck plans, cabin numbers, live prices or availability'), which implicitly routes price/availability questions to booking_facts or show_offers. Alternatives are only implied, not named.

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