Is the Tokina 17-35mm f/4 AT-X Pro FX Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 17mm f/4.0 test image. Observe the contrast and resolution of these results.
Is the Tokina 17-35mm f/4 AT-X Pro FX Lens set to 17mm f/4.0 sharper than the Canon EF 17-40mm f/4L USM Lens set to 20mm f/4.0? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.