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

Annotations already declare readOnlyHint=true, so the safety profile is covered. Beyond that, the description decodes the calculation_type enum values (0 per booking, 1 per person, 2 per night, 3 per person and night) and names the fields returned, which is meaningful behavioral context for interpreting results. It omits pagination/ordering behavior, keeping it short of a 5.

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?

One dense sentence that front-loads the resource and its scope, followed by the API route mapping. No filler, though the sentence is packed tightly enough that the calculation_type enumeration competes with the core purpose for attention.

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 compensates by enumerating the key return fields and their value semantics, and the readOnly annotation covers safety. What's missing is any indication of result volume, ordering, or whether add-ons are returned per property vs globally when apartment_id is omitted.

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 apartment_id parameter is documented in the schema ('Only add-ons for this property'), so the description's parallel phrase 'optionally for one property' adds no new syntax or semantics. Baseline 3 applies when the schema does the heavy lifting.

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?

Specific verb+resource ('List the bookable add-ons') with scope made explicit ('optionally for one property') and the returned fields enumerated (amount, tax, calculation type, applicable properties). It also distinguishes itself from nearby sibling listers such as smoobu_list_price_elements and smoobu_list_custom_placeholders by naming the concrete resource.

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 description implies usage via 'optionally for one property', which tells the agent the call can be scoped or left global, but it never states when to reach for this tool versus siblings or any prerequisite (e.g. that an apartment_id must first be obtained). Guidance is implied rather than explicit.

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