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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely useful context beyond that: a hard quota of 500 region ids/day and the row-per-geography output structure, which the agent cannot infer from the annotations.

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 sentences, front-loaded with the fetch action and resource, then aggregation levels, then return shape and quota. Everything earns its place, though the return-column enumeration partially duplicates the existing output 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?

With an output schema and full annotations present, the description need only carry source, quota and scoping context, which it does. It would be complete with a pointer to list_datasets for obtaining valid dataset ids and any note on region-id counting against the quota.

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%, so the schema already documents level, dataset, regions, vectors, max_rows and geo_hierarchy with formats and defaults. The description only restates regions/vectors/level at a high level and lists the extra population, dwellings and area columns, adding no syntax or constraint detail 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?

The description gives a specific verb (Fetch) and resource (Canadian census values from Statistics Canada) and enumerates the supported geographic aggregation levels, so an agent knows exactly what data comes back. It does not, however, name or contrast itself with its sibling censusmapper.census.list_datasets, which the schema references only indirectly via the dataset id example.

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?

Usage is implied rather than stated: you supply a dataset, level, regions and vectors. There is no explicit when-to-use or when-not guidance, no mention that dataset ids must first be obtained from censusmapper.census.list_datasets, and no routing away from neighbouring census/statcan tools.

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