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

Annotations declare readOnlyHint=false and openWorldHint=true, which is consistent with the optional photo-creation side effect, and the description does not contradict them. It adds useful output context (volume, weight, kitchen measures, photo and page URLs to cite) but does not mention the API-key requirement or that photo generation can mutate server state — that detail lives only in the schema.

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?

A single front-loaded sentence pairing the purpose with illustrative examples; the return-value list is compact and informative. The example string is long but each clause maps to a supported query type rather than padding.

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 carries the return-value burden and does so thoroughly (measures, plain-language size, photo URL, citation page URL). The gaps are minor: no disclosure of the API-key/auth need for photos and no indication of latency or failure behavior when a photo cannot be made.

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 baseline is 3, but the description genuinely enriches the query parameter by demonstrating the accepted input range: quantities with units, counts of objects, inverse questions, and A-vs-B comparisons. That goes beyond the schema's terse 'The question in plain words.'

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 states a specific capability — answering 'how big is it really?' for any amount or number of things — and backs it with concrete query archetypes ('50 grams of sugar', '1,000 ducks', 'chicken vs duck vs ostrich'). It never mentions the sibling get_page or clarifies the boundary between them, so it is clear but undifferentiated from alternatives.

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?

The example queries imply when this tool applies (size/mass/scale comparisons in plain words), which is real usage signal. However, there is no explicit statement of when not to use it, no prerequisites, and no routing guidance versus get_page.

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