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

With no annotations, the description carries the full disclosure burden. It clearly reveals statelessness ('no network, no password'), that the trip lives inside the link, and that the tool returns a new link. It stops short of declaring immutability of the original link or failure modes for invalid/malformed links, but the key behavioral traits are disclosed.

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?

Four sentences, each adding a distinct element: the action, when to use it, the input format/consequences, and the sibling alternative. Front-loaded and free of filler.

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 six-parameter tool with nested objects and no output schema, the description covers the primary operations and return behavior ('get the new link back'), and the schema fills in the details. However, it omits changing the origin as a listed operation, and interaction semantics like 'remove applied after add/legs' rely entirely on the schema, so it is adequate but not complete on its own.

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 each parameter is already well-documented. The description adds value by grouping the high-level operations (add, replace, rename, remove) and identifying the draft-link input, but it does not exceed the schema's per-parameter meaning.

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 states a specific verb and resource ('Update a trip link') and enumerates the operations: add legs, replace them, rename, drop one. It also names the sibling it is not (add_to_kept_trip), making selection unambiguous.

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 explicitly says to use this instead of build_trip_link when a plan changes, and explicitly directs KEPT links (#k=) to add_to_kept_trip. It also scopes input to draft links (#d=), so the agent knows exactly when this tool applies.

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