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

With no annotations provided, the description carries the burden for behavioral disclosure. It clearly states the operator-only restriction and idempotency (returns success with credits_granted=0 if already credited). However, it does not describe what happens if the invoice is not settled or other error conditions, though the output schema may cover those.

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 well-structured and front-loaded with purpose, then restriction, use cases, and idempotency. It is slightly verbose in the restriction paragraph, but each sentence contributes useful context. The use of bold for the restriction and separate paragraphs improves scannability.

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?

Given the existing output schema and fully described input parameters, the description covers the essential context: purpose, authority model, typical failure scenarios, and idempotent behavior. It is sufficiently complete for an agent to select and invoke this tool correctly in the intended situations.

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?

The input schema already provides 100% coverage with clear descriptions for all three parameters (dpop_token, invoice_id, patron_npub). The tool description adds contextual framing around operator involvement and idempotency, but does not meaningfully enhance the parameter-level semantics beyond what the schema already states.

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+source: 'Credit a patron's ledger from a BTCPay-settled invoice.' This clearly distinguishes it from sibling tools like brain_purchase_credits or brain_redeem_coupon by framing it as a manual reconciliation action for settled-but-uncredited invoices.

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 lists concrete use cases (cold-start vault races, ncred delivery hiccups, etc.) and explicitly restricts usage to the operator, with escalation guidance for patrons. While it does not name alternative tools to use first, it clearly implies this is a last-resort after normal payment verification has failed.

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