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

With no annotations, the description bears full responsibility for behavioral disclosure. It states the lookup action (implying read-only) and code formats, but does not mention edge cases, return behavior, or any other operational details. It is not misleading, but minimal.

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?

A single, clear sentence that front-loads the purpose and directly specifies the accepted inputs. Every word contributes to the meaning, and there is no redundant information.

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 simple lookup tool with a single parameter, the description is sufficient. The purpose and input format are fully stated, and an output schema exists to cover return values. No additional context is necessary for correct invocation.

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 0%, so the description must compensate. It does so by defining 'code' as an IATA (2-char) or ICAO (3-char) airline code, which is essential for correct parameter usage. This goes beyond the bare schema and gives the agent actionable format constraints.

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 action ('Look up an airline') and the specific resource, with precise input formats (IATA 2-char or ICAO 3-char). This differentiates it from airlines_search (which likely searches by name) and airports_lookup (which handles airports), making the purpose unambiguous.

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?

There is no explicit guidance on when to use this tool versus airlines_search or other alternatives. The phrase 'by IATA or ICAO code' implies usage when a code is available, but no exclusions or alternative tools are mentioned.

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