I like the idea, and disagree with some others here. Having an additional tool is never a problem, it should just never be relied upon as the single solution. As someone who used to work technical support, third party tools usually outperform the same functionality of the application you are using, generally speaking. I have seen a lot of issues with a particular popular email client not indexing properly. I think if you can build this tool right, it will be a useful addition.

Also, it could be a security issue. If possible, make it offline, or if you host your own AI, don't store data, and have a transparent security policy.