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

With no annotations provided, the description carries the full behavioral disclosure burden. It discloses the operator-only access restriction, idempotency (returns credits_granted=0 if already credited), and the context of BTCPay-settled invoices. This gives the agent a clear safety and idempotency profile beyond the basic write operation.

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 with a bold opening sentence, operator restriction callout, bullet-style use cases, and a concise idempotency note. Every sentence adds value, and the length is appropriate for the tool's sensitivity and complexity.

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 an operator-restricted credit tool with an output schema, the description covers purpose, authorization requirements, use cases, and repeat-safety. It omits failure modes, but the output schema and clear operator role make this complete enough for an agent to select and invoke 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%, with detailed descriptions for all three parameters (dpop_token requires an operator-signed Nostr event, invoice_id is the BTCPay invoice, patron_npub is the recipient). The tool description adds no additional parameter-level meaning, so the baseline 3 is appropriate.

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 starts with 'Credit a patron's ledger from a BTCPay-settled invoice,' which uses a specific verb and clearly identifies the resource and source. It distinguishes itself from sibling tools like excalibur_check_payment and excalibur_purchase_credits by focusing on manual restoration of credits.

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 the tool is RESTRICTED to the operator and provides clear escalation guidance for patrons. It lists concrete use cases (cold-start vault races, ncred delivery hiccups, early Top-Off sheet closure) that tell an agent exactly when to invoke this tool versus alternatives.

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