It's hard to judge what you are after, since attitudes and beliefs about an intervention cannot be content free and so I can't picture any (sensible) generic tool. Both attitudes and beliefs are likely to be quite specific so (for example) a tool asking someone their attitudes and beliefs about cars will likely have entirely different content to asking them about fruit. A tool to measure attitudes and beliefs about an intervention  are likely to have much content that is specific to that particular intervention. 

What might help you (either directly or indirectly) is to consider the approach to eliciting items (about attitudes, social norms and behavioural control) for a theory of planned behaviour questionnaire study. The content is specific to the target behaviour but the approach to eliciting items  (tool?) is common to all. There is probably a 'seminal' source out there but it doesn't come to mind but if you google: theory of planned behaviour elicitation you'll probably find something.

Theory of planned behaviour may or may not be directly relevant to you but the issue of getting content for any tool is I think relevant.

Peter

agree with Peter on the fact that attitude and belief scales are content oriented.

The content or the situation or intervention  (specify the attitude or belief towards which) you intend to measure. As the scale varies from situation to situation.

As it wont be appropriate to use one scale to all..as a matter of fact it would be irrelevant.

In case you are looking for a sample to formulate or understand the structure of an attitude or belief scale, you may find may of them by google search.

regards

Rathish

Thanks so much for your quick, insightful responses. I appreciate it very much.

Tanya