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

Annotations already declare idempotent=true, destructive=false, readOnly=false and openWorld=true. The description adds genuine behavioral context beyond them: 'Only the fields you send are changed' discloses PATCH-style partial-update semantics, which the annotations alone do not convey. It stops short of covering auth or conflict behavior.

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?

Three tight sentences, front-loaded with the verb and scope, followed by concrete edit examples and then the required identifiers. Every clause earns its place and nothing is padded.

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?

For a 6-parameter, nested-body mutation tool with no output schema, the description covers the essentials: what is editable, that kind selects the applicable fields, that keys come from get_trip, and that the update is partial. It does not explain the coupling between 'kind' and which data fields are valid (left to the schema), leaving a minor 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%, so every parameter (tripId, variantId, destinationKey, kind, optionKey) is already documented in the schema, including the optionKey/optionId aliasing note. The description reinforces that kind must be supplied and optionKey comes from get_trip, but adds no syntax or format detail beyond the schema. 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 (Edit) and resource (an existing accommodation, transport or getting-around option), then grounds it with concrete edit examples (price, booking link, check-in dates). The word 'existing' plus the enumerated kinds distinguishes it cleanly from the sibling add_*_option tools.

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 the key prerequisite explicitly — 'Say which kind of option it is and pass the option key from get_trip' — which routes the agent through get_trip before calling. It implies editing rather than creating, but never names the add/delete/select alternatives or states when not to use it, so it falls short of full routing guidance.

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