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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context beyond annotations: it returns two URLs (trip_url and trip_page_url) and discloses that 'package-only flight fares become bookable when the trip includes a hotel or experience.' This is useful, non-obvious 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?

The description is four sentences, front-loaded with the primary purpose. Every sentence adds information: what it does, when to use it, how to pass parameters, and return values/edge cases. It is denser than necessary but still concise with no fluff.

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?

Given the tool's moderate complexity (2 params, 1 required, output schema exists), the description covers the key aspects: inputs, outputs, when to use, and an important edge case (package-only fares). It does not mention error handling or prerequisites beyond 'fresh results,' but the output schema and annotations fill some gaps. Overall, it is sufficiently complete for an agent to select and invoke the tool correctly.

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% (both parameters have descriptions in the schema), so the baseline is 3. The description adds meaningful context beyond the schema by specifying that items are 'url values of the chosen flight, hotel, and/or experiences' and that they must come from 'fresh search results,' which adds clarity about the expected input format and freshness requirement.

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 states the tool 'assemble[s] a complete multi-part trip' into 'ONE bookable link with a single checkout,' which is a specific verb+resource. It is easily distinguished from sibling search tools, as this is the only tool that builds a trip rather than searching for items.

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 states when to use it: 'whenever the user wants to plan or book a whole trip rather than a single item.' It also implies a prerequisite (passing values from fresh search results). While it does not name an alternative tool explicitly, the 'rather than a single item' exclusion provides clear guidance.

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