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

Annotations only declare readOnlyHint=false; the description adds an 'opened shop page' prerequisite but does not disclose currency spend, irreversibility, purchase limits, or failure behavior. For a purchase mutation this leaves the central behavioral traits implicit.

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 with no filler; the parenthetical count note is compact. Slightly cryptic wording ('штучных товаров') costs it a point.

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 mutation with minimal annotations and no output schema, the definition is underspecified: cost/currency, success effect, and count semantics are absent. It gives enough to understand the basic call but not enough to call it safely in all cases.

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?

With 0% schema description coverage, the description at least explains that count is the quantity for piece items and ties item_id to an item on the open shop page. It still leaves item_id format/source and count defaults or edge cases unspecified.

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 verb ('Купить') and resource ('товар') and scopes it to an opened shop page, which helps separate it from vendor or auction purchase siblings. It does not explicitly name or compare against alternatives, 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?

It implies a prerequisite — the shop page must be open — but gives no explicit when-to-use or when-not guidance and does not mention alternatives such as vendor or auction purchases. The count note is helpful but is not usage routing.

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