Is the Canon EF-S 55-250mm f/4-5.6 IS STM Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 200mm f/5.6 test image. Observe the contrast and resolution of these results.
Is the Canon EF-S 55-250mm f/4-5.6 IS STM Lens set to 200mm f/5.6 sharper than the Tamron 18-200mm f/3.5-6.3 XR Di II LD Macro Lens set to 50mm f/4.5? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.