storekit__extend_renewal_date

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

Annotations already declare readOnlyHint=false and destructiveHint=true, so the write/destructive nature is covered. The description adds genuine value beyond that: it warns that the call changes billing and instructs the agent to confirm with the user first. It omits the idempotency/retry behavior implied by request_identifier, keeping it below a 5.

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 with zero filler. The purpose is front-loaded and the caution follows immediately, and the [App Store Server API] tag adds provenance without bloat.

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 mutation tool with no output schema, the description covers purpose, motivating scenario, and the key behavioral caution (billing impact / confirm first). It is nearly complete; elaborating on reversibility or the idempotency contract would make it fully sufficient.

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 100%, so all six parameters (including the reason enum and environment) are already documented in the schema. The description adds no parameter-level detail, so baseline 3 is appropriate.

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?

States a specific verb (extend) and resource (a subscriber's renewal date), plus the use-case scope (service gesture for an outage or support escalation). This clearly distinguishes it from read-oriented siblings like storekit__get_subscription_statuses and storekit__get_transaction_history.

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?

Gives a clear when-to-use context — outage remediation or a support escalation — which frames the very specific situation this tool exists for. It does not name an alternative tool or an explicit when-not-to-use, so it stops short of a 5.

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