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

Goes well beyond the read-only/idempotent annotations: local decoding with no upstream call, UTC day/hour with no month or year, unparsed groups surfaced in the response, 422 invalid_report on unreadable input (not charged), typical latency under 0.1s, price and free-tier quota. This is unusually rich operational context.

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?

Dense but front-loaded: the decode purpose and outputs come first, followed by input, caveats, and cost. Every sentence carries information, though the pricing/quota clause makes the block longer than strictly needed for tool selection.

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 compensates by enumerating the decoded fields (wind, visibility, weather, clouds, temperature/dew point, altimeter, flight category, TAF periods, `unparsed`). Combined with the error and cost notes, an agent has everything needed to call and interpret it.

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 both parameters are documented there (including the enum and the 2,000-character limit). The description mostly restates raw/kind and its 'auto detects it' behavior, adding the useful note that unrecognised groups land in `unparsed` but little parameter-specific 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 (decode) and resource (one pasted METAR or TAF report) and enumerates the decoded outputs, which clearly separates it from the fetch-oriented siblings get_metar/get_taf. An agent can tell it decodes supplied text rather than retrieving a report.

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?

Gives clear context: one pasted report, max 2,000 characters, and an explicit 'informational only: not for flight planning or navigation' exclusion. It does not name the alternative siblings (get_metar/get_taf) for retrieving reports, so routing is implied rather than stated.

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