Merchant Center data sources

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

Annotations already fully declare the behavioral profile (readOnly, idempotent, non-destructive, open-world), so the description owes little here. What it does add is only a content list; it says nothing about auth requirements, pagination, or how sources are keyed, so it contributes almost no behavioral context beyond the structured hints.

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?

One short noun-phrase line, front-loaded with the resource name and followed by the content categories. Nothing is redundant, though the fragment style means the action itself is left implicit.

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 zero-parameter read tool with no output schema, the description gives a reasonable hint at the returned fields but never states the shape of the result (list vs. single object, grouping, sorting) or scope limits. It is adequate but leaves the agent guessing about the response.

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 tool takes zero parameters, which sets the baseline at 4. The description's field list (labels, countries, languages, fetch URLs) is essentially descriptive metadata about the payload rather than a parameter explanation, so there is no gap to compensate for.

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 names a specific resource (Merchant Center data sources/feeds) and enumerates the content it covers (labels, countries, languages, fetch URLs), so an agent knows the domain. However, it supplies no verb at all — it never says whether the tool lists, fetches, or summarizes these sources — and it draws no boundary against the sibling merchant_report_query.

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 guidance, no prerequisites, and no mention of the adjacent merchant_* siblings (merchant_product_issues, merchant_report_query) that an agent must choose between. The agent is left to infer the trigger condition entirely.

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