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

Annotations already establish readOnlyHint=true, so the safety profile is covered. The description adds genuinely useful context beyond that: the underlying API mapping (GET /api/addons[/{apartmentId}]) and the interpretation legend for calculation type (0/1/2/3), which an agent could not infer from the schema. It stops short of mentioning pagination or rate limits.

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 dense sentence that front-loads the resource, then the returned fields, then the optional filter and API mapping. The parenthetical example list and enum legend cost little and add value; the trailing endpoint note is the only mildly expendable element.

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 carries the burden of describing return values, and it does: amount, tax, calculation type, and applicable properties. Combined with the 100%-documented input schema and readOnly annotation, an agent has enough to call it correctly; pagination behaviour is the one gap.

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% and the single parameter is already documented as 'Only add-ons for this property.' The description's 'optionally for one property' largely restates that, so the baseline of 3 applies with no meaningful added syntax or format detail.

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 (List) and resource (bookable add-ons) with concrete examples (towels, breakfast, late check-out) and enumerates the returned fields. No sibling tool covers add-ons, so the resource alone differentiates it from the list_apartments/list_price_elements family.

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?

Offers some guidance via 'optionally for one property', which implies the no-argument call returns all add-ons and the argument narrows to one property. However, there are no explicit when-to-use/when-not statements, no prerequisites, and no named alternatives among siblings.

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