MQTT-SN Tools is a suite of four command-line applications for working with the MQTT-SN (MQTT for Sensor Networks) protocol. The system provides mqtt-sn-pub for publishing messages, mqtt-sn-sub for subscribing to topics, mqtt-sn-dump for monitoring packets, and mqtt-sn-serial-bridge for serial-to-UDP bridging. All tools share a common C library (mqtt-sn.c/h) that implements the MQTT-SN protocol handling, including socket management, packet encoding/decoding, keep-alive mechanics, and topic mapping. The architecture is modular with clear separation between the protocol library and application-specific logic. Each tool follows a standard pattern: parse command-line arguments, establish UDP connection to an MQTT-SN broker, perform protocol operations (connect, publish/subscribe, etc.), handle incoming/outgoing packets, and clean up resources. The project has active maintenance with recent commits and a test suite.