The Text Tool is for selecting and editing text.
To select the Text Tool click its icon in the Toolkit panel, or choose menu option Edit > Select Tool > Text Tool (or keyboard shortcut ⌃T Control-T).
A shortcut way to select the Text Tool and insert the text cursor ready to begin text editing (with any of the Pointer Tool, Reshaping Tool or Rotation Tool currently selected) is to double click inside a shape or on a shape's outline path.
Drawing a rectangular text box (using Command-drag) or a shape from the Shape Library that is preset for text input (select a shape from the Shape Library, then draw using Command-drag) also selects the Text Tool and inserts the text cursor.
NOTE: You must enable a path before you can add text to it, using either the Text Along Path Tool or Text Flow Tool.