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

Beyond the read-only/idempotent annotations, it discloses a critical data constraint: two fare families (Google Flights return-trip two-adult searches vs easyJet one-seat one-way fares) must never be added together. It also clarifies that absence of a route is not evidence of no flight, which prevents a common misinterpretation.

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?

It is four dense sentences with no filler; the resource definition comes first, then the fare-family warning, then the filtering and absence caveat. The fare-family sentence is long but earns its place because the distinction is essential.

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 two-optional-parameter read tool with full annotations, the description covers what the records are (dated and sourced), how they can be filtered, and how to interpret missing routes. Without an output schema, it could say slightly more about the returned fields, but it is otherwise complete.

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%, so the baseline is 3. The description adds that filtering works with either parameter or both, reinforcing their optional nature beyond what the schema alone states.

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 opening sentence states a specific resource—airfares EclipseMission has read—and adds that each is dated and sourced. It is clearly a data-retrieval tool distinct from the sibling tools by resource type, but it never explicitly names or contrasts with them.

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?

It explains that filtering can be by departure airport, destination, or both, and warns that unread routes are absent rather than nonexistent. However, it does not say when to prefer this over plan_trip or compare_destinations.

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