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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive, and the description's 'Read-only' merely restates them. It does add that the response is scoped to a single tour and includes a computed party price and earliest availability, but omits error behavior for invalid slugs or unavailable tours.

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 tight sentence that front-loads the subject ('Details for one tour') and then lists the returned fields. Every clause carries information, though the trailing 'Read-only' is redundant against the annotations.

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 usefully enumerates the returned fields, which is exactly the context an agent needs to decide whether to call it. It stops short of mentioning failure cases or how the slug relates to list_tours output, but is otherwise sufficient for a two-parameter read 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%, so both parameters are fully documented in the schema itself, including the guests default of 2. The phrase 'the exact total for a party size' reinforces the pricing role of guests but adds no syntax or meaning beyond what the schema already supplies, so the 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?

States a specific verb and resource ('Details for one tour') and enumerates the payload it returns: inclusions, ages, fitness, gear, party pricing, and earliest bookable date. It is clearly not a list or booking tool, but it never names its siblings (list_tours, start_tour_booking) to draw the boundary explicitly, so it falls 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 listed contents (ages, fitness, what to bring, exact price, earliest date) imply a pre-booking research use case, but the description never says when to call this versus list_tours or start_tour_booking, nor does it state prerequisites such as resolving the slug first. Usage is inferable only.

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