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

Annotations already declare it is a non-read-only, non-destructive, open-world operation, so the safety profile is covered. The description adds one useful behavioral detail — purchaseToken is only needed for Android, not iOS — but says nothing about idempotency, re-verification behavior, or failure handling.

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?

A single front-loaded sentence with zero filler — the required-parameter enumeration is the payload and comes after the action statement. Slightly dense but nothing redundant.

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?

With an output schema present, return values need not be explained, and annotations cover mutation safety, so the remaining burden is purpose and inputs — both handled. The one gap is the side effect of a successful verification (e.g., whether credits are granted), which the agent might infer but the description does not state.

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 0%, so the description must carry the load, and it does name every parameter including the conditionally required purchaseToken ('for Android'). It adds the cross-field rule the schema cannot express, though it gives no format guidance (e.g., what a transactionId or packageId looks like).

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 ('Verify') and resource ('App Store / Play purchase'), and clarifies it is a server-side check equivalent to the mobile flow. It is distinguishable from sibling verify tools like ucode_payments_stripe_verify by naming RevenueCat/store, though it does not explicitly contrast with them.

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?

'Server-side verify ... (same as mobile)' implies the context of use — validating a store purchase after an app-store transaction — but gives no explicit when-to-use vs. when-not, nor does it name alternatives among the many sibling billing/payment tools. Usage is inferable rather than stated.

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