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

Annotations already declare readOnly, idempotent, non-destructive, open-world, so the bar is lower; the description adds real content beyond them, namely that the response includes licence, DOI and the full list of source data objects. It omits any note on cost, rate limits, or what happens when the optional selection filters match nothing.

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?

Three short sentences, purpose front-loaded, zero filler. The final clause exists specifically to differentiate from data answers, so it earns its place.

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 an output schema present, the description needn't detail return values, and it still conveys the substantive return contract (citation, licence, DOI, full sources). What's missing is default behavior when no selection filters are supplied, which matters given 7 optional parameters.

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%, so the description must compensate, and it does: the phrase "for a selection (stations, a time window, a box)" maps the otherwise-undescribed lat/lon min-max parameters into a coherent bounding-box concept and ties start/end to a time window. It also implicitly frames the optional parameters as an all-or-nothing selection rather than independent filters.

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?

Opens with a specific framing verb+resource ("How to cite a variable's data") and enumerates exactly what is returned: citation text, licence, DOI, plus full provenance objects for a selection. It explicitly distinguishes itself from the data-returning siblings by contrasting "short citation and only the COUNT of their sources" with "this lists them."

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 contrast with "data answers" gives a clear condition for choosing this tool (you need the full citation/provenance rather than the data itself). It does not name the sibling tool (get_data) directly or state exclusions such as "do not use when you just need values," so it falls short of explicit routing.

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