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

The annotations already indicate read-only, non-destructive behavior. The description adds meaningful behavioral context by explaining the output includes a plan plus links to run it as a group trip on Instafan, and that it draws from 'strongest real places'. No contradiction with annotations exists.

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 two concise sentences with no filler. The main action and resource are front-loaded, and the return-value detail earns its place.

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 low parameter count, complete schema coverage, presence of an output schema, and annotations covering safety, the description is sufficient. It explains what the tool does and what it returns, leaving no major gaps for an agent to call it 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 for parameters is 100%, so the schema fully documents 'destination' and 'days'. The description adds some conceptual color ('day-by-day', 'strongest real places') but does not provide additional parameter-level detail beyond what the schema already contains.

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 a specific verb ('Build'), a specific resource ('a day-by-day itinerary'), and a distinctive source ('its strongest real places'). It also mentions the return value, which distinguishes it from sibling tools like destination_brief, spot_photos, and top_spots.

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 makes the use case clear: generate a multi-day itinerary for a destination. It does not explicitly name alternative tools or state when not to use it, but the context is specific enough for an agent to select it appropriately among siblings.

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