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

With readOnlyHint: true and openWorldHint: false annotations, the description adds valuable behavioral context: it clarifies that seasonal and charter services carry no operating dates and should be treated as unverified for specific dates. It also notes the larger response when including airlines, going beyond the annotations to set expectations.

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 sentences, front-loaded with the core purpose, followed by precise details and a caveat. Every word earns its place, with no redundancy or 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?

Despite no output schema, the description fully covers the tool's behavior, including edge cases like seasonal service date limitations. For a tool with three parameters and a single required one, the description provides all necessary operational context without being overly verbose.

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%, providing baseline equality. The description adds meaning by explaining the effect of the 'kind' filter with examples and clarifying that 'include_airlines' results in a larger response, which is not obvious from the schema alone. This enhances the agent's understanding of parameter usage.

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 lists all airports reachable nonstop from a given origin, including service kinds, with optional filters. It uses specific verbs and resource nouns, and differentiates from sibling tools like 'reachable_from' and 'find_connections' by emphasizing nonstop routes.

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 clearly implies when to use the tool (to get nonstop destinations from an origin, optionally filtered by kind and with airline details), and provides context on behavior like larger responses. However, it does not explicitly exclude alternatives or mention sibling tools, though the context is clear.

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