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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds real context beyond that: the link is pre-filled with the guest's dates and party size, the destination is owner-operated (trust-relevant), and this is a fallback rather than a primary path. It does not describe failure modes or whether the referral is logged.

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?

A single sentence, but efficiently structured with the precondition front-loaded ahead of the action and payload. Every clause carries information (trigger, destination, ownership, pre-fill), though the parenthetical aside about the owner makes it slightly denser than necessary.

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 zero required parameters, full schema coverage and no output schema, the description covers the essential contract: when to call it and what it returns (a pre-filled referral link). It could still say whether any confirmation or follow-up is generated, but nothing critical for correct invocation 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 the schema already explains start, guests, nights, note and the nested requester object. The description only echoes that dates and party size are used to pre-fill the link — modest added value over the schema. 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?

The description names a specific verb ('return a link') and resource (Islands & Sails referral link from Dream On's sister concierge), plus what the link is pre-filled with. It is unmistakably distinct from siblings like check_availability, find_open_windows or get_quote, which all operate on Dream On itself.

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 states an explicit precondition ('Only after Dream On's own options don't work') and enumerates the two triggering conditions (group larger than 8, or no suitable open dates). This is exactly the when-to-use/when-not guidance an agent needs to route correctly.

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