What is the ruling on describing someone as an agent, and does this constitute slander?

Slander that necessitates a Hadd punishment is specific to the accusation of Zina (fornication/adultery) or the denial of paternity. Accusing someone of treason, meaning betrayal of the nation or espionage, is not slander that necessitates a Hadd punishment, but rather a vile form of insult and abuse. If it occurs in the absence of the innocent person, it is a calumny (buhtan); if it occurs in their presence, it is injustice, indecency, defamation, and aggression. The Prophet, peace and blessings be upon him, said: "A believer is not a slanderer, nor a curser, nor an obscene person, nor a foul-mouthed person." And he said: "Insulting a Muslim is فسوق (disobedience/wickedness)." However, if the described person truly deserves such an accusation, then warning against them is religiously and rationally required. It must be noted that accusing people based merely on suspicion is forbidden, as Allah Almighty says: "O you who have believed, avoid much [negative] assumption. Indeed, some assumption is sin." (Quran 49:12), and as the Prophet, peace and blessings be upon him, said: "Beware of suspicion, for suspicion is the falsest of speech."