You don't have to come up with a clever excuse. Agents know that writers contact others with fulls and give them the opportunity to offer or pass. The agent who offered for me outright told me he expected me to go contact the other agents. You would just tell the offering agent that you need x amount of time to consider their offer.
If the reason you're not sure about the agent is because you've done research since querying and realized that they are not the agent for you or because they told you what they wanted in revisions and you realize that that doesn't mesh with your vision of the book, then maybe you want to wait. But really, why? I can see no reason to wait to contact the other agents with fulls just because you're not sure about whether you're going to accept the first agent's offer. Here's why:
- If you tell the other agents, it's going to force them to actually look at that manuscript that's been sitting on their desk waiting to be paid attention to.
- If they've been on the fence, the fact that someone else thinks it can be sold might tip the scales in your favor
- It's very unlikely they're going to reject a ms they like just because there was an offer on it (see point above this)
- If the reason you're only considering the offering agent is that she's your, say, third favorite of those who requested fulls, #1 and #2 agents aren't necessarily going to get back to you in a reasonable amount of time unless you give them a reason to.
- Once you talk to the offering agent and any new offering agents, you might realize that it's one you hadn't really given much consideration to who is your new favorite (or you may realize that the original is better for you)
What would be the reason to wait?
