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

No annotations are provided, so the description carries the full burden. It discloses that the call is free, no credits required, and requires proof of npub ownership to prevent front-running. This provides useful behavioral context beyond a simple 'check status' description.

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 concise with no redundant sentences. Every line provides essential information: action, sequence, cost, and security requirement.

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 an output schema exists, the description provides adequate context: the sequence (post-purchase), the security requirement, and cost. It explains the dpop_token parameter in detail. The tool is simple enough that no further explanation is needed.

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%, but the description adds value by explaining the invoice_id comes from purchase_credits and that npub links the purchase. This supplements the schema's own descriptions.

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 states 'Check the payment status of a Lightning invoice' which is a specific verb+resource combination. It also mentions this is called after paying from purchase_credits, distinguishing it from sibling tools like schwab_purchase_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?

Explicitly says 'Call after paying the invoice from purchase_credits' and mentions prerequisites (npub proof). However, it does not explicitly name alternative tools for related tasks.

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