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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds meaningful behavioral context beyond that: the tool has two modes (listing all invoices vs. retrieving commissions for a specific invoice based on invoice_id). This conditional behavior is not captured in annotations and is valuable for the agent.

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 two sentences, with the primary action front-loaded and the optional behavior introduced in the second sentence. There is no filler or redundancy. Every word contributes to understanding the tool's function and the parameter's role.

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 tool with one optional parameter, no output schema, and annotations covering safety, the description is largely complete. It states what the tool returns (list of invoices or commissions), and the 'creator's' clarifies scope. It doesn't describe the response format or pagination, but given the simplicity and lack of output schema, this is a minor gap. The agent can likely infer the list structure from the name and description.

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 compensate. The single parameter invoice_id is explained in the description: 'Pass an invoice_id to get the individual commissions that made it up.' This conveys the parameter's purpose and its effect on the output, which is sufficient for a string ID. It doesn't specify format or constraints, but for a simple ID that's acceptable. It fully covers the parameter's semantics beyond the bare schema.

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 uses a specific verb and resource: 'List the creator's Stripe invoices.' It clearly states the primary action and resource, distinguishing it from sibling tools like split_get_earnings or split_list_discount_codes by focusing on Stripe invoices. The additional clause about invoice_id adds a secondary purpose without confusion.

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 provides clear context on when to use the tool: to list the creator's Stripe invoices, and optionally to drill into a specific invoice's commissions. It does not explicitly name alternatives or state when not to use it, but the context is sufficient given the uniqueness of the resource (Stripe invoices). No exclusions are mentioned, which fits the 4-level of 'clear context, no exclusions'.

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