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

With no annotations provided, the description carries full behavioral disclosure. It reveals read-only nature, cost per call, error_type values with retry guidance, flight_number normalization, and a precondition health check. This level of transparency is exceptional.

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 dense but every sentence adds value. It is front-loaded with the core purpose and then systematically covers input, output, coverage, data window, health check, error handling, and cost. No filler or repetition.

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 compensates by listing all output fields and error types. It also covers prerequisites, restrictions, retry logic, and pricing. For a tool of this complexity, the description is fully self-contained.

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?

Although schema coverage is 100%, the description adds meaningful semantics: it shows the exact input structure, explains flight_number case-insensitivity and normalization, lists output fields, and details error_type meanings that affect retry behavior. This far exceeds the schema's own descriptions.

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 starts with a specific verb and resource: 'Returns live flight status from ACSA (airports.co.za)'. It clearly distinguishes itself from sibling tools by naming the coverage (JNB, CPT, DUR) and the data source, making the tool's unique purpose unmistakable.

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?

Provides explicit when-to-use context: limited to three South African airports, 48-hour data window, and read-only (no booking/ticketing). It also instructs to call the /health endpoint first and not proceed if structure_valid=false. This goes beyond mere context to actionable guidance.

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