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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so safety is covered. The phrase 'once the PNG is rendered' adds the useful readiness/async nuance, but the description never explains the not-ready case — does it error, return a pending status, or block? That is the key behavioral unknown for a polling tool.

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?

A single front-loaded sentence with zero filler; the verb, target, and eventual result are all in the first clause.

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 return value burden falls on the description, and 'return a download capability' is underspecified — expiry, pending/ready distinction, and polling cadence are all missing. Adequate for a simple status check but with clear 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?

One parameter (exportId) with 0% schema description coverage — the schema only gives a UUID format and pattern, no meaning. The description never mentions exportId or where it comes from (presumably the export-prepare call), so it fails to compensate for the coverage gap.

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?

Specific verb+resource: 'poll a map image export' and returns a download capability for the PNG. Clearly a status-check companion to map_image_export_prepare, but the description does not name that sibling explicitly, so differentiation is inferred 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?

'Poll' implies repeated invocation after an export is prepared, but the description never says when to call it (only after map_image_export_prepare?), how often to poll, or when to stop. Usage 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.