This paper introduces a minimal toy model that links cosmic acceleration to the informational structure of the universe, using the Mutual Information Density Hypothesis (MIDH) and the informational-inertia conjecture developed in earlier work. Instead of treating inertia as a primitive property of matter, MIDH interprets it as the correlation-reconfiguration cost required to update internal and boundary information under acceleration. If this cost decreases as the universe expands and large-scale mutual information densities thin out, then the Friedmann acceleration equation naturally acquires an additional term that behaves like dark energy, without requiring a cosmological constant or any exotic vacuum fluid. By assuming a simple scale-factor dependence for the “interface capacity” μ(a), the model yields an effective constant term mathematically identical to Λ in ΛCDM and reproduces the observed transition from deceleration to acceleration around z ≈ 0.6. The paper does not propose a replacement for ΛCDM. Instead, it offers the smallest and most transparent bridge between MIDH’s structural interpretation of inertia and cosmological dynamics. It shows how late-time acceleration can arise as a consequence of the universe’s decreasing ability to maintain correlated structure at large scales.