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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds value the annotations cannot: it names what the returned figures actually are (part counts by category, SKU count with a display price), which matters because there is no output schema. It omits any handling notes for unknown brands or the brand_shop flag.

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 compact sentence with no filler, and the overview-vs-detailed distinction is front-loaded. The semicolon-clause structure is slightly dense but nothing is wasted.

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?

For a 2-parameter, zero-required read tool with no output schema, the description covers the main branching and hints at return contents. It leaves the second parameter (brand_shop) entirely unaddressed and gives no sense of result shape or size, so an agent must fall back on the schema for half the call.

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% and both parameters are documented in the schema, including the 'only drivestock is live' caveat, so the baseline is 3. The description restates the brand omit/pass behavior and adds the result semantics, but says nothing about brand_shop that the schema does not already say.

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 this returns catalog statistics and spells out the two result shapes (all-brands overview vs. per-category part counts plus SKU display-price counts), which is more specific than the title alone. It does not explicitly contrast itself with the sibling list_brands, so an agent still has to infer that list_brands enumerates brands while this one aggregates numbers.

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?

It gives a clear conditional rule: omit brand for the overview, pass brand for the detailed breakdown. That is genuine when-to-do-what guidance. It offers no exclusions or cost/pagination caveats, and it never mentions the brand_shop parameter's usage.

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