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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, so safety is covered. The description adds real behavioral context beyond that: paging via limit (default 25)/offset, the CSV variant trick, that every value carries its source citation and checked quote, and the analytic warning never to read a trend across a definition break.

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?

Front-loaded with what the tool returns, then slug sourcing, then paging/filtering, then format hint. Dense but every clause carries information; the parenthetical breaks warning and the slug examples are justified. Slightly packed in the first sentence but not wasteful.

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 helpfully enumerates the return shape (values, labels, publisher/title/page/URL, exact quote, breaks) and paging behavior. There is no auth or rate-limit note, but for a read-only idempotent lookup tool the coverage is sufficient to call it correctly.

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 0%, so the description must compensate, and it largely does: it explains limit default 25, offset, the from_year/to_year/category/subgroup narrowing axes, and gives concrete slug examples. It doesn't clarify what category/subgroup values are valid or how the slug is formatted beyond examples, leaving some gaps.

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+resource: retrieves one GPS Historical Data series by year, with the exact payload contents (values, source citation, quote, breaks). It also implicitly distinguishes itself from list_historical_series by telling the agent where to get slugs, so the two siblings are separable without opening either schema.

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?

Explicitly routes the agent to list_historical_series for slugs and tells it how to narrow results (from_year/to_year/category/subgroup) and request CSV. It doesn't state when NOT to use it (e.g. multi-series or keyword discovery cases), so it falls short of a full when/when-not/alternative rubric.

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