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

Annotations already declare readOnly, idempotent, open-world and non-destructive, so the safety profile is covered. The description adds that results are probabilistic — a range plus a confidence — which is genuinely useful, but it says nothing about what happens when all inputs are empty or how image_url and image_base64 interact.

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, front-loaded with the action before the return values, with no filler. The second sentence enumerates return fields that the output schema already documents, which is mild duplication but keeps the description self-contained at the point of selection.

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?

With six optional parameters, zero required, and a rich output schema, the definition is nearly complete — return values need not be re-explained. The gap is that it never states that at least one of title or an image is needed, nor which image field wins when both are supplied, so an agent could call it with nothing.

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%, so every parameter is already documented and the baseline is 3. The description only maps its phrasing ('from a photo or a name') onto the title/image families without adding precedence rules or format constraints beyond the schema.

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 scope ('prices one item') plus the two accepted input modes (photo or name), which lets an agent tell it apart from compare_prices in practice. It never names either sibling explicitly, so the differentiation is inferred from 'one item' 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?

Usage is only implied: 'one item' hints this is the single-item path while compare_prices presumably handles several, but no when-to-use or when-not-to-use rule is given. There is also no guidance on choosing this over where_to_buy_or_sell when the user wants valuation plus a selling channel.

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