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

The annotations already mark the tool as read-only and non-destructive, which covers the primary behavioral safety traits. The description doesn't add much new behavioral detail (e.g., rate limits, specific API quirks), but it provides strong contextual framing for the data type itself. Given the hints, a 3 is appropriate as the description adds contextual value without unnecessary repetition of security/mutability traits.

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?

The description is focused and efficient, dedicating the text entirely to defining the resource type and its business logic constraints. It avoids redundant phrasing and is structured logically.

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?

While the tool is complete for its specific purpose, it lacks guidance on the expected format of the returned add-on data (e.g., whether it's a flat list or nested objects containing the price, duration, etc.). Adding a note on the response structure would enhance completeness, but it is strong for a listing tool.

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%, meaning the schema already details both `business` and `location_id`. The description offers no additional meaning or semantic constraints beyond what the schema provides, resulting in the baseline score of 3.

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 clearly defines what 'add-ons' are within the business context (a treatment extra, a longer session) and what the tool fetches. It successfully distinguishes this concept from general services or offerings.

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 provides a specific use case constraint: 'never booked alone,' implying they are always paired with a main service. It also dictates their location ('on the booking page'), which guides the agent on *when* to use them versus other list/booking tools.

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