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

With no annotations supplied, the description carries the burden and does well: it discloses the returned aggregate fields, notes the verdict is "based only on that history" (setting expectations about its limited basis), and states "No sign-in required" — a genuine auth constraint an agent would otherwise have to discover. It stops short of describing failure modes for unknown product ids or any rate limits.

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 tight sentences: the capability and identifier forms come first, the return payload and auth note follow. No filler, no repetition of the title, and every clause carries information.

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 description properly compensates by enumerating the returned fields, and all six parameters are covered by the schema. The remaining gap is minor: nothing explains behavior when no history exists for a given product or how the verdict is derived beyond "based only on that history".

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% for all six parameters, so the description's restatement of identifier forms (Prickelly id, shop id, or product URL) is largely redundant with the schema. It adds no semantics the schema lacks, such as how days interacts with the verdict or how marketplace is resolved, so the baseline 3 applies.

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 definition states a specific verb and resource ("Get price history for one product") and scopes it to a single product by id or URL, which immediately separates it from the multi-result siblings like search_products and get_deals. It also names what comes back (points, min, max, current, verdict), so an agent knows the tool's output shape before opening the schema.

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?

Usage is implied by the "for one product" phrasing and the accepted identifier forms, which suggests this replaces a search when the product is already known. However, there is no explicit when-to-use or when-not-to-use statement, and no sibling (get_deals, search_products, add_watch) is named as an alternative path.

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