Evaluation details

The evaluation is always provided from the point of view of the current side to play. It always takes one of two formats:

• +/-x.xx for normal positions. The number indicates the advantage or distadvantage measured in pawns. A positive number represents an advantage for the side to play, while a negative number represents a disadvantage. An evaluation of +0.00 would be considered a totally equal position.
• Mx or -Mx for positions where a forced checkmate has been found, with x being the number of full turns until checkmate under perfect play. Mx means that the side to play is checkmating their opponent, while -Mx means that the current player is getting checkmated.

Current caveats

When a position has only one legal move, in order to save time, the engine skips evaluation entirely and returns an evaluation score of +0.00 regardless of the actual dynamics of the position.

For example, in the following position with white to play:

The move Qh5+ leads to a forced checkmate, and thus the engine's suggestion is d1h5 with an evaluation of M2.

The only legal move for black is g6:

Which is checkmate after Qxg6, however, the engine would return an evaluation of +0.00 for the move g7g6 for black, despite it very clearly leading to checkmate, since it is the only legal move.

This doesn't really affect the strength level of the engine, since it only occurs when the engine receives a request to evaluate a position with only one legal move, not in the search process for other positions. It would only affect the evaluation shown in a front-end, but I'm still not very sure how to tackle this.