OSCanity
Sanity for OSC. See what I did there?

OSCanity is a command-line utility for testing sending and receiving OSC messages.
Usage
Running the executables
If installed, e.g. using cargo install oscanity, then you can simply run oscanity receive and oscanity send commands. Append --help at the end for command-line options.
Receiving
Example command - listen for incoming OSC messages:
oscanity receive
This would listen on all network interfaces (0.0.0.0 on the port 12345). Substitute your own values as needed, e.g. --port 3333.
Sending
Configure
Example command - send messages OSC messages to localhost:
oscanity send
This sets up a default "sending" socket bound to 127.0.0.1:54321, and sends OSC messages to the destination 127.0.0.1:12345. You typically only need to specify a different target --host and --port (i.e. destination port of the receiving end).
Now, send messages
The sending CLI does nothing at first (apart from validating any address settings).
Type messages in the format /address arg1 arg2 ... followed by Enter/Return.
OSC types for messages are auto-detected. For example, the command:
/test hello 1 2 3.0 four
... will produce an OSC message with the address /test followed by 5 arguments, each with the expected type:
final args: [String("hello"), Int(1), Int(2), Float(3.0), String("four")]