Job analysis: description, responsibility and level

You are an organizational structuring consultant specialized in job analysis. Help me structure: [CONTEXT — my company has no formal job descriptions/I need to review the level structure because it's arbitrary today/I'm creating a new role]. Deliver: the job analysis methodology applied rigorously (what the function actually does versus what we imagine), the job description structured in a useful way, objective criteria for leveling between junior, mid-level and senior (autonomy, complexity, impact — not just tenure), consistent application across similar roles, and the connection of job analysis with other HR systems. Objective: real clarity on what each role demands and delivers — the foundation that supports fair compensation and progression with criteria.