Create an invoice

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

Annotations mark this as a non-read-only, non-destructive, open-world write with idempotentHint=false; the description adds the crucial nuance that idempotency is conditional on supplying the same amount plus reference, and clarifies that omitting it always produces a new invoice. It also discloses the return payload (checkoutUrl). It does not mention auth, rate limits, or invoice expiry, so it stops short of full transparency.

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?

Four short sentences with the purpose front-loaded, followed by the idempotency rule and the follow-up tool. Every sentence carries distinct information and nothing is repeated from the schema.

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 the essential contract: what is created, the currency constraint, the deduplication rule, and the primary returned field. Missing lifecycle details (expiry, how the buyer receives the link) are minor given four well-documented parameters.

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 the baseline is 3, but the description adds genuine meaning the schema lacks: reference functions as a deduplication key tying the same amount to the same invoice rather than just a webhook echo. The store and returnUrl parameters are left to their schema descriptions.

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 and resource ("Creates a Stablevoy invoice") and bounds the scope (paid in USDT or USDC), then names the concrete artifact returned (checkoutUrl). It is clearly distinguishable from siblings get_invoice, list_invoices, and list_stores.

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?

Explicitly routes the agent: supply a reference when possible to avoid duplicate invoices, and use get_invoice to check status later. It gives a concrete naming example ("acme-october"). It does not discuss store selection or when not to create an invoice, leaving that to the schema.

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