[Write] Add a new App Store metadata locale

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

With no annotations, the description carries the burden of behavioral disclosure. It reveals that the operation fails if the locale exists, supports dryRun, and notes that fields can be filled in later via asc_metadata_update. It does not mention authorization or return values, but the core write behavior and error condition are disclosed.

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 three sentences, front-loaded with a 'Write.' prefix, followed by clear purpose, error condition, and key feature (dryRun). Every sentence adds value without redundancy.

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?

Given 10 parameters, 3 required, no output schema, and no annotations, the description provides a solid overview of the tool's operation, failure mode, and relationship to asc_metadata_update. It does not mention success return values, but that is less critical for a create operation. The description is sufficiently complete for an agent to select and invoke the tool correctly in most cases.

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 only 40%, so the description must compensate. It conveys that fields are optional and provides an example for locale, but it does not elaborate on the six optional metadata fields (keywords, whatsNew, supportUrl, etc.). The field names are fairly self-explanatory, but the description adds limited parameter-level detail beyond what the schema already gives for appId, locale, version, and dryRun.

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 verb ('Creates') and resource ('a new localization for a version') with a concrete example (adding ja to en-US). It also distinguishes itself from the sibling asc_metadata_update by explicitly noting that it is for new locales, while updates are for existing ones.

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?

The description explicitly states when to use this tool (new localization), when it fails (if locale already exists), and points to the alternative asc_metadata_update for existing locales. It also clarifies that fields are optional now or later, reinforcing the intended usage.

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