Write to contact@mytoolstash.dev. Bug reports and accuracy issues get priority — please include the tool name and the input that produced the wrong result so it can be reproduced and fixed quickly.
Tool suggestions
New tools are added regularly. If you describe the calculation or conversion you need and where you'd use it, useful suggestions often go live within a couple of weeks.
Response time
MyToolStash is maintained by an independent developer, so replies usually take a day or two. Every message gets read.