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

Annotations already declare readOnly, idempotent, closed-world and non-destructive, so the safety profile is covered. The description contributes behavioral context the annotations cannot: the exhaustive breadth of returned data ('everything Cassette knows'), which matters because there is no output schema. It omits what happens when the slug is unknown or the game has no demo/price, a minor gap.

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, zero filler. The content enumeration comes first and the usage trigger second, so the agent reads the scope before the routing hint. Every clause carries information.

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 one-parameter read tool with strong annotations and no output schema, the description covers both what is returned and when to reach for it, which is what an agent needs to act. The only missing piece is error behavior for an invalid or unmatched slug, which is a small omission given the tool's simplicity.

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% and the schema already explains that 'game' is the slug returned by search_games, including the cross-reference to the sibling. The description adds no format, casing, or fallback guidance for the identifier, so it does not exceed the baseline set by a fully documented single parameter.

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 names the resource precisely ('one game') and enumerates what comes back: description, facts, price, demo, maker, screenshots, store page and play link. That is far more informative than the title 'Get one game'. It lacks an explicit retrieval verb, but the scope is unambiguous enough that an agent can distinguish it from list-style siblings.

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?

'Use it before you recommend a game you only know from a list' gives an explicit trigger condition and implicitly routes the agent away from acting on thin list data alone. It does not name the alternatives (search_games, similar_games) or state when-not to use it, so it falls short of full when/when-not/alternatives guidance.

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