get_item

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

No annotations are provided, so the description carries the full burden, and it does meaningful work: it discloses the ID-format constraint ('bare numbers do not work') and enumerates the returned fields. It still omits auth/permission requirements and error behavior for unknown or inaccessible ids, which is a gap for an unannotated tool.

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?

Three sentences, front-loaded with purpose and the id constraint before routing and return details. The return-field list is long but earns its place because there is no output schema.

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 no output schema, enumerating the returned fields (title, price, quantity, status, pictures, attributes) is exactly the right compensation, and sibling routing is covered. Only permission/error context is missing, which keeps it short of a 5.

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% for the single parameter, so the baseline is 3; the description goes slightly beyond by warning that bare numeric ids fail, which the schema only implies via the example. That extra constraint is genuinely actionable.

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 and resource ('Get full details of a single Mercado Livre listing by its item id') and explicitly contrasts itself with the sibling get_my_items. An agent can distinguish it from bulk/seller-scoped siblings without opening any schema.

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 when ('inspect a specific listing (yours or a competitor's) in depth') and names the alternative with the condition that selects it ('For bulk listing of the seller's own items use get_my_items instead'). Both the positive and negative routing cases are covered.

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