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

The annotations already establish readOnlyHint=true and destructiveHint=false, so the description does not need to restate safety. It adds useful behavioral context beyond the annotations: what the render actually contains (location, styles, title panel, legend) and a hard cap of 1,000,000 total pixels that the schema's per-dimension maxima do not enforce.

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?

It is front-loaded with what the tool produces, followed by sizing guidance. The conversational second-person phrasing is slightly wordy, but every sentence carries information about defaults, aspect ratio, or limits.

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?

For a read-only preview renderer with full schema coverage and no output schema, all the information needed to call it correctly is present: default size, aspect-ratio options, and the total pixel constraint. Only the exact return format (for example, whether the image is inline or a URL) is left unstated.

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 id, width and height, which sets the baseline at 3. The description adds orientation-based sizing advice (taller for north–south maps, wider for east–west) and the 'what fits on screen' semantics, which is genuinely more than the schema says; that could justify a notch above baseline, but the core parameter meanings still come from 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 states a concrete verb+resource: it renders a picture of a map created by create_map so it can be checked before sharing. That clearly separates it from create_map and update_map. It never names get_map_spec, so the differentiation from that sibling is left implicit.

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 a clear use context ('to check it before you share the link'), which tells an agent when this tool applies. It does not name an alternative or state when not to use it, so the routing guidance is useful but incomplete.

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