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

Annotations already declare readOnlyHint, idempotentHint and non-destructive, so the safety profile is covered. The description adds the return contents (estimate, new/used ranges, confidence), but that is largely duplicated by the existing output schema, and it says nothing about failure modes, auth needs or 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 sentences, zero filler: usage trigger and input modes first, routing exclusions second. Well front-loaded and every clause earns its place.

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 an output schema present, the description needn't restate return values, and with annotations carrying the safety profile, the definition covers what an agent needs to select and call the tool. Input modes, scope, and sibling routing are all present.

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 each of the six parameters is documented in-schema, so the baseline is 3. The description's 'photo or a name' phrasing loosely maps to image_url/title/image_base64 and the optional nature of inputs, but adds no format or precedence detail 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+resource (price an item) and the input modes it accepts (photo or name) in the first sentence. It immediately distinguishes itself from compare_prices and where_to_buy_or_sell by naming both as out of scope.

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 an explicit triggering condition (user wants to know what one item is worth, with a photo or name) plus explicit exclusions with the correct alternative for each ('weigh new against used (compare_prices)', 'list stores (where_to_buy_or_sell)'). No inference required to route between the three tools.

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