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

With no annotations, the description carries the behavioral burden, and it discloses the key external side effect: the authenticated account matching site_id will own the new listing and OAuth2 write scope is required. The examples use 'publish,' implying a live marketplace action. It doesn't discuss reversibility, fees, or review processes, but the core write behavior and auth requirement are transparent.

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?

The description is compact and front-loaded: a one-sentence action, a bolded auth caveat, a bolded prerequisite, and two concrete examples. Every line earns its place and there is no filler.

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?

The description covers the essential invocation context: authentication scope, account ownership, category prerequisite, and site selection via examples. An output schema exists, so return-value documentation is not required. It could mention that the listing becomes publicly visible or the defaults for site_id/account, but those are either implied or available in the schema.

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?

The prose adds useful semantic guidance: category_id should come from predict_category/list_categories, and site_id is mapped to countries in the examples. However, it doesn't enumerate the required fields (title, category_id, price, available_quantity) or the 'input' wrapper, so parameter understanding depends heavily on the nested schema. Given the stated 0% schema coverage, this is only partial compensation.

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 opens with a clear verb-resource pair: 'Create a new product listing on MercadoLibre.' It adds platform context and the word 'new' helps separate it from update/relist siblings, though it doesn't explicitly name an alternative for modifying existing listings.

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 provides concrete usage conditions: OAuth2 write scope is required, and category IDs should be obtained from predict_category/list_categories first. The natural-language examples clarify when to use the tool with specific site_id, price, and category values. It doesn't explicitly state exclusions like 'use update_item for existing listings,' so it stops short of full routing guidance.

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