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

Annotations already declare readOnly, openWorld, idempotent, and non-destructive behavior. The description adds meaningful behavioral context: 'cached flight tickets' indicates data may be stale, 'one per destination, cheapest first' specifies ordering and cardinality, and the example clarifies parameter usage. These go beyond the generic annotations and help the agent understand what to expect.

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 plus an example. The main purpose is front-loaded, and the example illustrates usage efficiently. There is no fluff or redundancy. It 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 there is no output schema, the description could have explained what the return data looks like (e.g., a list of tickets with prices, airlines, dates). It also omits details about caching freshness or limitations. However, for a read-only tool with clear annotations and a well-documented schema, the description is adequate but not fully complete—missing the return format is a noticeable gap.

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%, so the baseline is 3. The description adds an example call but does not explain parameters beyond what the schema already provides. It reiterates IATA codes and shows the destination/currency usage, but this is largely redundant with the schema descriptions. The example is a minor value-add for understanding parameter interplay.

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: 'Get the cheapest cached flight tickets for a route'. It clearly distinguishes this from siblings by mentioning 'one per destination, cheapest first' and 'Uses IATA city/airport codes'. Even without an explicit comparison to travelpayouts_cheapest_by_month or price_calendar, the purpose is unambiguous and precise.

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 does not provide explicit when-to-use guidance or contrast with alternatives like travelpayouts_cheapest_by_month or travelpayouts_price_calendar. It implies usage through the example, but no exclusions or selection criteria are given. An agent would infer that this tool is for quick price checks on a specific route, but there is no explicit guidance.

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