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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered without help. The description adds a small amount of output context (values are numeric and carry units) but says nothing about the shape of the comparison, whether missing properties are omitted or nulled, or how units are chosen.

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?

Nine words, front-loaded with the comparison and ending with the constraint most likely to cause an error (units). It wastes nothing, though the fragment construction leaves the central action implicit rather than stated.

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 3 fully described parameters and read-only annotations, the essentials are covered, but there is no output schema and the description does not explain what the comparison returns (per-property rows vs. per-element blocks) or how missing properties are handled. For a tool whose entire value is the result format, that is a real gap.

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 all three parameters (locale, elements, properties) are already documented inline, including accepted element formats and the enum of properties; baseline 3 applies. The description adds only the "2-10 elements" bound already encoded in minItems/maxItems and the "numeric" hint about the default property set, nothing new.

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?

"Side-by-side numeric properties of 2-10 elements, with units" names the resource (elements), the operation (side-by-side comparison) and a hard scope limit (2-10), which separates it from get_element/list_elements/search_elements without opening a schema. It is a fragment rather than a full verb phrase and never names the siblings explicitly, so it stops short of a 5.

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?

There is no when-to-use statement and no mention of the alternatives (get_element for a single element, search_elements for discovery). The comparison intent is merely implied by "side-by-side"; an agent must infer from the name and the 2-10 bound that this is the multi-element path.

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