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

Annotations already establish readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds real behavioral value beyond that: output is a watermarked screen-size image, not the full-resolution paid render, and it costs nothing — useful for deciding whether to preview or export.

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 short sentences, front-loaded with the render/watermark/return fact and then the why and the cost. Nothing is padding.

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?

No output schema exists, and the description does cover that the return is an image, but it omits format/mime details. For a 15-parameter tool that mirrors make_map, the shared-request statement plus free/watermarked framing is nearly complete, with only minor return-format gaps.

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 80%, so the schema already documents nearly all 15 parameters. The one genuinely useful addition is that rendering happens at screen size, which implies the dpi parameter is not honored the way it is for make_map, but this is left to inference rather than stated.

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 (render), resource (the map), output form (image), and the distinguishing trait (PREVIEW watermark, screen size). It also explicitly relates itself to the sibling make_map by saying the request is identical, so an agent can tell preview from purchase at a glance.

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?

Gives clear context — see the layout before buying — and notes it is free and shares make_map's request shape. It does not explicitly say 'use make_map when you are ready to buy', so the alternatives routing is implied rather than stated.

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