create_invoice_no_amount

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

With no annotations, the description carries the full burden. It does disclose the key behavioral trait (amount is intentionally unset and payer-determined), but says nothing about default expiration, whether a bolt11 request is returned, or any wallet/permission prerequisites for creating the invoice.

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 short sentences, zero filler, with the defining constraint ('without a specified amount') front-loaded before the explanatory clause.

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?

The schema is fully self-documenting and there is no output schema to explain, but for a state-creating tool with zero annotations the description leaves the agent guessing about the returned artifact and expiration defaults, which matters for wiring the invoice into a payment flow.

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 four parameters including the required wallet_id and expires_in are already documented in the schema. The description adds no syntax, units, or default values beyond that, so the baseline 3 applies.

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?

Specific verb + resource ('Create a Lightning invoice') with a qualifying scope ('without a specified amount / open invoice'), which effectively separates it from create_invoice and create_invoice_usd. It stops short of naming those siblings explicitly, so the differentiation is inferred rather than stated.

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 phrase 'The payer can choose how much to send' implies the use case (open/tip-style invoice), but there is no explicit when-to-use vs. when-not, and no named alternative such as create_invoice or create_invoice_usd for fixed-amount flows.

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