Does cycling a card count as casting a spell?

Cycling is an activated ability of the card itself, not a spell being cast. When you cycle a card, you pay its cycling cost and discard it as part of activating that ability — the card never goes on the stack as a spell (CR 702.29a, 702.29b).

Because cycling is an activated ability, it uses the rules for activated abilities (CR 602.1) rather than the rules for casting spells (CR 601.2). This means effects that trigger or interact with 'casting a spell' — such as a Counterspell or a triggered ability that says 'whenever you cast a spell' — do not interact with cycling at all.

However, some cards have triggered abilities that specifically watch for cycling. For example, Astral Slide says 'Whenever a player cycles a card…' — this trigger works precisely because the designers had to call it out separately from spell-casting triggers.

Concrete example: You control a creature with 'whenever you cast a spell, put a +1/+1 counter on it' and you cycle a Miscalculation by paying {1}{U} and discarding it. No spell was cast, so the creature's ability does not trigger and it gets no counter.

Key rules: CR 702.29a defines cycling as an activated ability; CR 602.1 covers how activated abilities are activated; CR 601.2 covers what it means to cast a spell — these are distinct game actions.