How the label is assigned
Mrigashira is the 5th of 27 equal nakshatras. Its interval begins at 53°20′ and ends just before 66°40′ of the sidereal zodiac. A planet or ascendant in that interval receives this label.
Each nakshatra is 13°20′ wide and contains four padas of 3°20′. The pada is calculated from the same sidereal longitude. No language model is needed to assign it.
How to use this reference
The traditional lord sequence gives Mars for Mrigashira. This is a classification within the chosen system, not a physical property of the sky.
Compare exact degrees and ayanamsa settings before concluding that a different tool is wrong. A position very close to a boundary can receive a neighboring label under a different method.