All too willing is an expression that refers to someone's eagerness to do something, typically without questioning or hesitation. In terms of synonyms, there are several words that could fit the bill. One option might be eager, which conveys a similar sense of enthusiasm. Another possibility is enthusiastic, which suggests a high level of interest and excitement. Willing could also be replaced with the word eager, which has a similar connotation. A more negative synonym might be overeager, which implies a lack of judgment or discretion. Ultimately, the choice of synonym will depend on the specific context and intended meaning.