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 adds real value by stating the output is a shareable URL that routes the end user to duoly.gg to pay, but it omits link lifetime, whether any reservation is held, and whether it requires prior availability checks.

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 tight sentences with the returned artifact front-loaded and no filler. The second sentence could be trimmed slightly, but nothing is redundant.

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?

An output schema exists, so return values need not be explained, and annotations cover safety. However, with four of six parameters undocumented anywhere and no guidance on prerequisites or link expiry, the definition leaves gaps for a tool whose output drives an external payment flow.

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 only 33%: game and service carry descriptions, while rank, region, currency and quantity have none. The description reinforces only the two documented parameters ('the game and service selected') and says nothing about rank, region, currency or the 1-10 quantity bound, so it fails to compensate for the coverage gap.

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 a concrete artifact and its effect: 'Get a bookUrl that opens Duoly with the game and service selected.' That is specific enough to distinguish it from siblings like get_quote or get_availability, but it never explicitly contrasts itself with them, so it stops short of a 5.

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?

The second sentence implies the workflow ('Share it for the user to review remaining options and pay on duoly.gg'), which tells an agent this is a hand-off step after options are chosen. It gives no explicit when-not or reference to alternatives such as get_quote, and the dependency on list_games/list_services appears only in the schema, not the description.

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