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

Annotations already declare a safe, read-only, idempotent operation, and the description adds substantial behavioral detail beyond them: the row shape, the meaning of `id` as a slug for the current edition, the meaning of `regionCount`, the effect of `labels: false` on `style.labels`, and how `layers` relate to `render_map`.

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?

Although the description is multi-sentence, it is densely front-loaded and nearly every sentence conveys a distinct operational fact: return shape, id semantics, regionCount, labels, layers, query behavior, and usage constraint. There is very little waste.

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?

There is no output schema, so the description carries the burden of explaining return values, and it does so thoroughly via the row shape and field semantics. It also covers id reuse, query usage, and unknown-id behavior, making the definition complete for an agent 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 coverage is 100%, and the schema already documents that `query` searches ids, titles, region types, and categories with examples. The description largely repeats that same semantic content rather than adding syntax or constraints beyond what the schema provides, so the baseline of 3 is appropriate.

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 opens with a specific verb and resource: 'List the maps Ultimaps can render,' then enumerates the map families. It also distinguishes its role from sibling tools by explaining that the returned `id` is the input for `render_map` and `get_map_regions`.

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?

It gives explicit when-to-use guidance: 'Only call this when you don't know the id,' notes that common ids like `world` and `united-states` already work, and states the fallback behavior for unknown ids. That is unusually clear routing guidance.

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