No, you can't rely on just the USPTO's search tool when clearing your trademark, because the tool's search function is extraordinarily limited.
In a recent presentation, I talk about calls I receive from clients who are running a search on uspto.gov and concluding that a trademark is ok to use and register.
This can lead to very expensive problems down the road (such as having to re-brand).
A proper trademark clearance search, which requires a few hours and the proper tools, looks for trademarks that might be similar but not the same as yours.
For example, problematic trademarks can include:
• Trademarks with similar meaning
• Trademarks that share a word in common with yours
• Trademarks that are phonetically similar
• Trademarks that are famous and have broader protection than seems obvious.
Don't believe me? Run a search on "NYKE" on uspto.gov.
It shows you two results. None of them are NIKE.
But I guarantee you that if you file a trademark for NYKE, you are going to have an issue.