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A pay-per-use fax service that uses Lightning Network payments (L402 protocol) for authentication and billing. Allows sending faxes via PDF URL or text content.
Single tool 'send-fax' has a well-structured schema with proper types, enums, and descriptions. Tool name is action-oriented (send_). Description is clear and mentions L402 auth requirement. However, the description is relatively brief (127 chars, below the 194-char baseline for A+ tools), and lacks guidance on when to use it, what it returns, or error recovery paths. Parameter descriptions are present and mostly specific (e.g., 'E.164 format'), but lack detail on failure modes and retry behavior. No output schema is documented, callers must infer response structure from examples. Error handling is implicit in examples (status field, refund object) but not formally specified in the tool definition.
Send a fax via PDF URL or text content to a phone number. Requires L402 authentication (Lightning Network payment).
Output schema not documented. Tool definition lacks formal specification of response fields (status, fax_id, refund, etc.). LLMs must infer structure from examples.
Tool description lacks recovery guidance. Does not explain what to do on failure, which errors are retryable, or how to claim refunds. Examples show refund.lnurl_withdraw but tool description does not mention it.
Parameter 'pages' lacks bounds documentation. Description says '1-350' but no min/max constraints in schema. LLMs may pass invalid values outside this range.
Conditional parameter dependencies not formally documented. 'pdf_url' is required when mode=pdf, 'text' required when mode=text, but schema does not enforce this (no oneOf or conditional validation). Examples show manual validation in client code.
| Scored | Grade | Overall | Spec posture | Rubric |
|---|---|---|---|---|
| 2026-09-23 | D | 52 | 2026-07-28+ | v2 |
No error classification or actionable error messages specified. Tool description does not explain what errors are possible (invalid phone, PDF fetch failure, payment rejection, etc.) or how to recover.