Abstract: A downhole tool assembly is configured for repeated and selective hydraulic activation and deactivation. A spring member biases the indexing control section 210 towards a first axial position while drilling fluid pressure in the tool body urges the indexing control section 210 towards other axial positions. Downhole tool activation and deactivation may repeatedly be controlled from the surface by cycling the drilling fluid pressure.

Abstract: A system provides for the remote activation and deactivation of a downhole tool such as an agitator tool. The downhole tool uses a dart-catching section configured with a profile that engages with a corresponding key section of a dart. Different tools in the string may have different profiles, allowing darts to pass through tools to reach a tool with a matching profile further downhole. The dart includes a removable nozzle that can be detached by a object dropped from the surface, after which a second dart may be dropped to engage with the first dart to change operating parameters of the tool.