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

Annotations already declare read-only, non-destructive, open-world behavior, so the description does not need to repeat safety details. It adds useful context about billing-date filtering and pagination via cursor, though it does not discuss permissions or response shape.

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 compact and front-loaded: it states the filtered resource first, then explains pagination, then gives the endpoint. Every sentence adds value without unnecessary repetition.

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 read-only list tool with full parameter documentation and annotations, the description covers the key behavior: billing-date filtering and cursor pagination. It does not describe response fields, but no output schema is provided and the core invocation needs are satisfied.

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 100%, so all three parameters are already documented in detail. The description reinforces the date-range semantics and cursor workflow, but adds little beyond what the schema already explains about formats and pagination.

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 defines the resource and filter: subscriptions with at least one billing attempt scheduled between two UTC date-times. It distinguishes this from a generic subscription list by focusing on billing dates, though it does not explicitly name the sibling `list_subscriptions` as an alternative.

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 a concrete use case: seeing what will be charged tomorrow or this week. That gives clear context for when to use the tool, but it does not specify when not to use it or name an alternative for listing all subscriptions.

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