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

Adds real context beyond the annotations: the call is a cheap pre-flight that does not transfer the data itself, and it reports rows, stations and time span. Annotations already cover read-only/idempotent/non-destructive, so the description's job is this cost/return framing, which it delivers. It doesn't mention latency or cost 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?

Two short sentences, front-loaded with the outcome and trailing with the sequencing rule. Every word earns its place with no restatement of the name or schema.

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?

An output schema and full annotations reduce what the description must carry, and the purpose plus sequencing rule are sufficient to invoke it correctly. The gap is filter semantics for the geo/height/QC parameters, which an agent must infer from bare schema names.

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 coverage is only 50% — lat/lon bounds and height bounds carry no descriptions anywhere, and the description never mentions them or the semantics of cruise, apply_qc or start/end exclusivity. The phrase 'rows, stations, time span' hints at output dimensions rather than explaining any of the 12 parameters, so it does not compensate for the coverage gap.

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 the concrete outcome (size of a selection: rows, stations, time span) and the key property that it happens 'without fetching it'. It also names the sibling it precedes, so an agent can tell it apart from get_data without inspecting schemas.

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 explicit workflow guidance: 'Call this before get_data,' which tells the agent when this tool belongs in a sequence. It does not state when to skip it or what the alternative is if an estimate is unnecessary, so it stops short of full when/when-not coverage.

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