Storefronts worth checking

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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive. The description adds configurable behavior tied to an environment variable and clarifies that results are a subset of all possible Apple storefronts, going beyond what annotations express.

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 short and front-loaded with the core meaning. The note about Apple operating storefronts for most countries is slightly general but still helps explain why any two-letter code may be passed elsewhere. No wasted sentences.

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-only configuration listing tool with rich annotations, the description is sufficient to select and invoke it. It explains the source, the scope, and the configuration knob. A return-format example would be nice but is not essential.

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?

There are zero parameters and schema coverage is 100%, so the baseline is 4. The description adds useful context about what the returned values represent (two-letter storefront codes) even though no parameters need explanation.

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 clearly identifies the resource (storefronts) and the specific scope (the working set this server sweeps by default, plus the configured default). This distinguishes it from the long sibling list, none of which cover storefronts.

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 tells the agent this is the working set, not the full list, which prevents over-generalizing. It also explains the set is configurable via APPLE_PODCASTS_STOREFRONTS. It lacks an explicit alternative tool reference, but no sibling tool offers the same capability.

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