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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world. The description adds real operational context beyond them: the setup call itself needs no key and consumes no quota, while tile counting occurs when the map is actually viewed, and the embedded key must be domain-restricted. That is meaningful behavior disclosure, though it lacks detail on output shape or limits.

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 tight sentences, front-loaded with what is produced. The one rough edge is the juxtaposition of 'Replace YOUR_KEY with a key' and 'Needs no key,' which is resolvable (the call needs no key; the generated snippet does) but momentarily ambiguous.

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 steps in to describe the return values (HTML/JS snippet or URL template) and covers key and quota implications. Missing only minor details such as the exact form of the snippet output, which an agent could infer.

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 both parameters have enum descriptions, so the schema already carries the variant semantics. The description reinforces library choice and adds the practical note that YOUR_KEY must be replaced with a website-restricted key, but adds little beyond the schema about 'style.'

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 uses a specific verb and resource: it returns ready-to-paste HTML/JavaScript for an interactive zoomable map, or a raster tile URL template. The phrase 'interactive, zoomable' implicitly separates it from static_map, but no sibling is named explicitly, so the differentiation is inferential 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?

It explains clearly which variant to pick: MapLibre for vector, Leaflet or OpenLayers for raster, and tile_url 'for any other library.' That is useful routing among options. It never says when to choose a sibling such as static_map instead, so there is no explicit exclusion guidance.

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