Can I add my accounts using the investor password?

Yes — but only in specific cases on Social Trader Tools.

The MT4/MT5 investor password provides read-only access to an account. It allows the platform to view trades, but not execute or modify them.

Because of this:

• Lead (Copy-from) accounts: can be added using the investor password
• Follower (Send-to) accounts: require full trading credentials (login + trader password)

Follower accounts must be able to open, modify, and close trades in order to properly mirror the master account. If a follower is added using investor access, copying will fail or trades will not execute correctly — commonly showing as an execution error (e.g. error 133/10017) in logs.

In short:

• Investor password → OK for reading signals (lead accounts only)
• Full credentials → required for trade execution (follower accounts)