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

With no annotations, the description carries the full burden. It does add real behavioral signal by disclosing PATCH semantics (partial update, only supplied fields change) and that the operation is scoped to a single locale. However it says nothing about required auth/credentials, whether the localization must already exist, or what happens if an empty required-free payload is sent.

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?

Two sentences, no filler, with the scope constraint front-loaded before the exclusion clause. Every clause carries information the agent needs to route the call.

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 five-parameter mutation with no annotations and no output schema, the description covers purpose and scope but leaves the identifier parameter and the failure/no-op behavior unexplained. An agent can still call it, but may not know how to source app_info_localization_id or whether missing fields are cleared or preserved.

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 description coverage is only 20%, so the description must compensate, and it does partially by naming three of the five fields (app_name, subtitle, privacy_policy_url) as the updatable set. It says nothing about app_info_localization_id, the identifier that actually selects what gets patched, nor how to obtain it, and it omits notification_message entirely.

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 gives a specific verb (update) plus the exact resources (localized app name, subtitle, privacy policy URL) and even names the API operation (PATCH app info localization). It clearly scopes the tool to listing-page text rather than media, though it never names its closest sibling update_version_localization to disambiguate the two localization tools.

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 states when to reach for it ('text shown on the App Store listing page') and adds an explicit exclusion ('not screenshots'), which routes the agent away from upload_screenshot/delete_screenshots. It stops short of naming the true alternative, update_version_localization, leaving the boundary between the two localization tools to inference.

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