Is the Tokina 11-20mm f/2.8 AT-X Pro DX Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 11mm f/4.0 test image. Observe the contrast and resolution of these results.
Is the Tokina 11-20mm f/2.8 AT-X Pro DX Lens set to 11mm f/4.0 sharper than the Canon EF-S 10-18mm f/4.5-5.6 IS STM Lens set to 10mm f/4.5? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.