facebook_ads_countries

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

No annotations provided, but description accurately states it returns a list of country codes (read-only). With no parameters, there is little else to disclose. The description is straightforward and not misleading.

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?

Single, well-formed sentence with no filler. Every word adds value.

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 tool without output schema, the description fully explains what it returns and its purpose. No missing information for an agent to invoke it correctly.

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?

Tool has zero parameters, so baseline score is 4. Description adds no parameter details, but none are needed as schema covers 100% (empty object).

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?

Description uses specific verb 'Get' and resource 'list of supported country codes', clearly distinguishing from sibling tools that search or retrieve other data. The context 'for Meta Ads Library filtering' adds specificity.

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?

While no explicit when-not or alternatives mentioned, the description implies usage before filtering ads by country. Given the tool's simplicity and zero parameters, the context is clear enough.

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