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

Annotations already declare readOnly, idempotent, closed-world and non-destructive, so the safety profile is covered. The description adds real behavioral value beyond them: it discloses the sort order (newest to oldest) and what each capture contains (currency and stock state), which an agent could not infer from annotations alone. Rate limits or history depth limits are not mentioned, but maxPrecios in the schema covers volume.

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 short sentences, both load-bearing: the first defines the payload and its ordering, the second establishes the data lineage for the required parameter. Nothing is redundant.

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 two-parameter read-only tool with full schema coverage, rich annotations and no output schema, the description should characterize the return shape, and it does so briefly (prices ordered by recency, plus currency and stock state). Only minor gaps remain, such as whether the history is paginated or bounded in time.

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%, and the description's only parameter-relevant statement, that `entryId` comes from `radar_search_listings`, is already present in the schema's own parameter description. Thus it adds little meaning beyond the structured fields, making the 3 baseline correct.

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 names the resource precisely: observed prices for a single publication, ordered newest to oldest, with currency and stock state per capture. An agent can distinguish it from radar_compare_retailer_prices or radar_check_stock_outages, though the verb is implied by a noun phrase rather than stated outright.

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 supplies a useful workflow hint by stating that `entryId` comes from `radar_search_listings`, which implies this is a follow-up call after a search. However, there is no explicit when-to-use/when-not guidance and no comparison against siblings that also deal with prices.

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