Tool feasibility is a critical issue for generating a complete fixture assembly plan to reduce production setup time. Previous fixture design systems rarely consider the assembly tool feasibility. Current methods of assembly tool feasibility analysis mainly depend on simulation-based or user-interactive approaches, which rely on users’ judgment. This paper presents a new approach to tool feasibility analysis for fixture assembly planning. The fixture workspace around a tool is represented by a newly defined global accessibility sphere with depth of a truncated half-line. The assembly tools are modeled as five articulated parts to fully describe the tool characteristics. Tool feasibility analysis is executed to verify assembly tools’ feasibility applied on a fastener. In particular, both tool motion and tool placement constraints during tool applications are integrated into the tool geometric reasoning. The example demonstrates the fast computing speed and intuitive simulation of several assembly tools applied in fixture assembly.