Small JSON surface
No multipart requirement for the first live path: agents pass a reachable document URL.
Agent fax API
A fax tool schema agents can use safely.
Fax is irreversible enough that generic HTTP wrappers are not enough. AgentFax adds a dry-run path, stable idempotency, strict E.164 validation, structured errors, and small machine-readable docs.
Dry-run by default
Agents can validate every parameter and preserve an audit trail before sending.
Retry-safe operations
Network retries and model retries do not create duplicate faxes when idempotency is used.
llms.txt and OpenAPI
Agents can discover the smallest correct usage pattern from the API itself.
Signed webhooks
Delivery events can be pushed back to tools with timestamped HMAC signatures.