  We report the AGILE observations of GRB 220101A, which took place at the
beginning of 1st January 2022 and was recognized as one of the most energetic
gamma-ray bursts (GRBs) ever detected since their discovery. The AGILE
satellite acquired interesting data concerning the prompt phase of this burst,
providing an overall temporal and spectral description of the event in a wide
energy range, from tens of keV to tens of MeV. Dividing the prompt emission
into three main intervals, we notice an interesting spectral evolution,
featuring a notable hardening of the spectrum in the central part of the burst.
The average fluxes encountered in the different time intervals are relatively
moderate, with respect to those of other remarkable bursts, and the overall
fluence exhibits a quite ordinary value among the GRBs detected by MCAL.
However, GRB 220101A is the second farthest event detected by AGILE, and the
burst with the highest isotropic equivalent energy of the whole MCAL GRB
sample, releasing E_iso=2.54x10^54 erg and exhibiting an isotropic luminosity
of L_iso=2.34x10^52 erg/s (both in the 400 keV - 10 MeV energy range).
  We also analyzed the first 10^6 s of the afterglow phase, using the publicly
available Swift XRT data, carrying out a theoretical analysis of the afterglow,
based on the forward shock model. We notice that GRB 220101A is with high
probability surrounded with a wind-like density medium, and that the energy
carried by the initial shock shall be a fraction of the total E_iso, presumably
near 50%.
