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

With no annotations provided, the description carries the full disclosure burden. It does this well by revealing three important behaviors: the tool is restricted to the operator's signed dpop_token, it is idempotent, and if the invoice is already credited it returns success with credits_granted=0. This exceeds the bare schema and gives the agent dependable expectations about repeated or unauthorized calls.

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 front-loaded with the core action, then organizes the restriction, use cases, and idempotency into clearly separated paragraphs. Every sentence adds operational value, and the bullet-style use-case list is compact yet informative. No filler or redundancy is present.

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?

This is a sensitive mutation-like tool with an authorization restriction, an idempotency guarantee, and several nuanced trigger scenarios. The description fully covers who may call it, why it may be needed, and how it behaves on duplicate calls. Since an output schema exists, return-value details are already structured, so nothing essential is missing for an agent to invoke it correctly.

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 the schema already documents invoice_id, patron_npub, and dpop_token clearly. The description adds context about the operator-only auth requirement and idempotency, but it does not materially extend the per-parameter meaning. Baseline 3 is appropriate because the structured schema does the heavy lifting.

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 opens with a specific verb-resource pair: 'Credit a patron's ledger from a BTCPay-settled invoice.' It clearly distinguishes this from the 90+ sibling tools by naming the exact recovery scenario and stating the operator-only restriction. The purpose is unambiguous and not just a restatement of the tool name.

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 explicitly states when the tool is appropriate: cold-start vault races, ncred delivery hiccups, closed Top-Off sheets, and infrastructure incidents where a BTCPay invoice settled but the ledger was never credited. It also gives a firm when-not: only the operator may use it, while patrons must escalate to support. These conditions are specific enough for an agent to decide correctly.

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