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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds substantial context beyond them: it enumerates return components (per-line prices, online discount, off-peak pricing, on-site total), extra fields (notIncludedOptions, thresholdNudge, possibly empty), and the exact error envelope with four named error codes.

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?

Purpose is front-loaded in the first clause, and the return/error details are packed tightly with no filler. It is somewhat dense and prose-blocked rather than enumerated, but every sentence carries information.

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 fully compensates by describing both success shape (line prices, discounts, totals, optional arrays) and failure shape (error + message with named codes). For a six-parameter quote tool, an agent has everything needed to call and interpret it.

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 already 83%, so the baseline is 3; the description goes further by explaining the conditional interaction (off-peak when date AND timeSlot are given) and tying paymentMethod to the online discount. It does not clarify formatting for the pattern-constrained date/timeSlot beyond the schema, so it is not a 5.

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 precise verb+resource: the exact charge a booking would apply to a basket of services at one centre for a vehicle category. It is clearly a pricing/quote operation, distinguishable from siblings like start_booking or get_booking without inspecting either schema.

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?

Gives real context: off-peak pricing applies only when date and timeSlot are supplied, and it explicitly excludes promo codes (entered on the booking page instead). It never names an alternative sibling tool or states the pre-booking timing, so it stops short of full when/when-not routing.

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