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

Goes well beyond the annotations: it discloses cost (1 unit), the auth requirement (API key or connected account), output permanence and CDN caching/sharing, and that the REST route redirects. Those are exactly the operational facts annotations cannot express. There is a mild tension with idempotentHint=false, since 'built once and then shared' implies repeat calls resolve to the same file, but this describes file construction rather than the operation result, so it is not a contradiction.

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?

Effectively two sentences: the first front-loads what is produced and returned, the second covers use cases, cost, sharing and auth. No filler, and the most decision-relevant facts (formats, detail, URL) lead.

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 still tells the agent exactly what comes back (a permanent public CDN URL rather than geometry in the response), plus cost and auth prerequisites. For a three-parameter export tool this covers everything needed to call it correctly and interpret the result.

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% and the schema already documents the id formats, the four detail levels with point counts, and each format. The description only restates the format list and references 'a detail level' without adding meaning, which is the expected baseline when the schema does the work.

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 and resource ('Builds a boundary's polygon as a file'), enumerates the five supported formats and the detail-level dimension, and makes the output explicit (permanent public CDN URL, REST route redirects). It stops short of naming the sibling it contrasts with (get_boundary for inline geometry), so the differentiation from siblings is implied rather than stated.

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?

'Use it for large polygons, GIS tools and bulk downloads' gives a clear when-to-use context, and 'each file is built once and then shared' explains why repeat exports are cheap. There is no explicit when-not or named alternative (e.g., use get_boundary instead when you just need the geometry inline), so the agent must infer the boundary case.

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