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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds substantial behavioral context on top: the return shape (lowest, median, highest per stay length), the gating rule (only returned when at least 3 prices were read), inclusion of the dates read, the exclusion of per-operator prices, and the data source (Park & Keep index). That is well beyond what the annotations provide.

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?

It is front-loaded with the usage trigger, then example phrasings, then the return contract, and every sentence carries information. The list of example phrasings is slightly verbose but functional rather than filler.

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?

There is no output schema, so the description carries the return-value burden and does so fully: it explains the three statistics, the per-stay-length granularity (3/7/14 days), the minimum-data gating, the returned dates, and what is deliberately excluded. Nothing needed to call or interpret the tool is missing.

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?

With a single parameter and 100% schema description coverage, the schema already documents that 'airport' accepts an IATA code or a city/airport name. The description implies a European-airport scope but adds no format or matching details beyond the schema, so the baseline 3 applies.

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 (return the lowest/median/highest public parking price per stay length for a European airport) and adds a scope constraint ('Never a price per operator'). It does not explicitly name or route against its siblings airport_market_snapshot and airport_parking_options, so it stops short of full sibling differentiation.

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?

It gives a clear trigger ('Use this when the user asks how much parking costs... or whether a parking price is normal there') plus concrete example phrasings in multiple languages. It lacks explicit when-not-to-use guidance or pointers to the sibling tools, which is the only gap.

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