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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuinely useful behavior beyond that: the asynchronous timing ('about 20 seconds later') and the fact that results land in the background, which helps an agent decide when to re-poll.

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?

Two dense sentences with no filler, and the audience/scope qualifier ('For a signed-in user') is front-loaded. The second sentence is somewhat run-on, slightly reducing readability.

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?

Covers the async polling lifecycle, the input provenance and the return shape (by reference to price_item) despite there being no output schema. For a read-only tool with full annotations, this is close to complete, with only the explicit alternative-sibling routing left implicit.

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%, so both parameters are already documented, including scan_id's provenance and the cost bounds. The description largely restates scan_id's origin ('account.scanId a photo price returned'), adding only the timing correlation, so the baseline 3 is appropriate.

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 ('the finished result for a scan on their account') and ties the return shape to the sibling price_item. It doesn't explicitly contrast its purpose against get_sold_comps or price_item, so sibling differentiation is partial rather than explicit.

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 two concrete invocation triggers: polling with account.scanId after a photo price reported comps still loading (~20 seconds later), or re-reading a saved scan. This is clear when-to-use context, though it stops short of naming an explicit alternative or exclusion condition.

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