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

Annotations already cover read-only and non-destructive behavior, but the description adds a meaningful behavioral trait: a cost of 2 credits per call. It also confirms the response fields, though return details are partly redundant with the output schema. It does not cover error behavior or rate limits, keeping it from a 5.

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 front-loaded and efficient, delivering the core purpose in two sentences. The only waste is the redundant repetition of the tool name at the start ('Airport Code Converter: Airport Code Converter is...').

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 one-parameter converter with an output schema, this description provides enough to call it correctly. It omits error handling and sibling-tool distinctions, but those are minor for this tool's complexity.

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%, and the schema already documents the single 'code' parameter with letter counts and an example. The description's mention of submitting either a 3-letter IATA or 4-letter ICAO code adds no meaning 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 verb (converts) and resource (airport codes between IATA and ICAO), making the core function clear. It does not distinguish itself from related siblings like AirportsLookup or AirlineLookup, so it falls short of a 5.

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 explains that you submit either identifier to receive details, which implies usage. However, it gives no when-to-use guidance relative to alternatives such as AirportsLookup, nor any exclusions or prerequisites.

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