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

Annotations already establish read-only, idempotent, closed-world, non-destructive behavior, so the bar is lower. The description still adds real context: the data is authoritative (regulators' published lists) and it clarifies the permit taxonomy (scheduled airline holds a scheduled permit, not a charter permit), which prevents misinterpretation of results.

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?

Two compact sentences, front-loaded with the resource and what it returns. The permit-kind clarification and sibling handoff each carry weight; nothing is padded.

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?

With no output schema, the description usefully enumerates the fields an agent will get back, and the permit-kind note covers the main ambiguity in results. Pagination/ordering behavior is unstated, but the limit parameter and annotations cover most of what an agent needs to call this 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%, so city, limit, market, and category are fully documented there. The description only restates that filtering is by market, base city, or aircraft size, adding conceptual framing but no syntax or edge-case detail beyond the schema.

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?

States a specific retrieval ('Licensed operators from the regulators' published lists') with the filter dimensions and even enumerates the returned fields (name, base city, licence type, permit kind, fleet, models, profile page). It distinguishes itself from request_quote by framing that tool as the trip-booking path.

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?

Explicitly routes the agent away from this tool for trips ('For trips, use request_quote'), which is a real when-not-to-use rule. It doesn't address other siblings like list_aircraft or list_markets, but the schema already points to list_markets for valid market values.

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