It's effectively one-way. The developer seems to have given up on it:

nostr:naddr1qvzqqqr4gupzptujz495l5qzjfqrzwr0wyenkzhajaq6qah4cuutcfsr5k6e6eclqyfhwumn8ghj7am0wsh82arcduhx7mn99uq3wamnwvaz7tm9vdkxjurnv5h8qatz9aex2mrp0yq32amnwvaz7tmwdaehgu3wdau8gu3wv3jhvtcqre2xsetnv5k5yunfv3nk2uedfejk2epd2ahhy6ed8pax2eeh0gqsepwq

I suggest using momostr.pink , which is more difficult to use, but seems to actually work for 2-way communication with Mastodon.