nwc_make_invoice

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

With no annotations provided, the description takes on full responsibility for behavioral disclosure. It explicitly states that the tool 'does not move funds; only generates a payment request,' addressing the key safety concern for a financial tool. It also reveals the return values ('Returns the bolt11 string and payment hash'), which is helpful. However, it does not mention other behavioral aspects like whether the invoice is stored, persisted, or has side effects beyond generation, so it falls short of a perfect score.

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 long, front-loaded with the core action, followed by a concise safety note and return value summary. Every sentence earns its place with no fluff or repetition. The structure is efficient and scannable.

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 simple 3-parameter tool with no output schema, this description covers the essential aspects: what it does, its safety profile, and what it returns. It does not explicitly state whether the invoice is persisted or usable immediately, which could be relevant context for integration. However, the tool's purpose is straightforward and the description is sufficient for an agent to invoke it correctly in most cases.

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%, meaning all three parameters (amount_sats, description, expiry_seconds) are fully described in the schema with types and limits. The description adds no additional meaning beyond what the schema already provides—it simply mentions 'amount in sats,' which is already in the schema. Per the rubric, the baseline of 3 applies when schema coverage is high, and the description neither compensates nor introduces ambiguity.

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 states a specific action: 'Create a bolt11 Lightning invoice for the given amount in sats.' This is a unique verb+resource combination that unambiguously distinguishes it from sibling tools like pay_invoice or lookup_invoice, which serve different functions. The resource (bolt11 invoice) is specific and leaves no doubt about the tool's purpose.

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 no explicit guidance on when to use this tool versus the siblings. It does not say 'use this when you need to receive payment' or contrast with pay_invoice. The phrase 'Safe — does not move funds; only generates a payment request' hints at its non-destructive nature, but this is more about safety than usage context. There is no mention of appropriate scenarios or exclusions, leaving the user to infer from the tool name and sibling list.

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