This would be a great improvement to have.  At the moment, if you're using the pipeline DSL for an SBT project, the options that I'm aware of are:

• something like what's described in this Gist: https://gist.github.com/muuki88/e2824008b653ac0fc5ba749fdf249616
• something really horrible, like
  def SBT = 'java -Dsbt.log.noformat=true -jar `find ~/tools/ -executable -type f -name "sbt-launch.jar"`
  sh "${SBT} compile test"

In my view this lack of compatibility between Jenkins fundamentals, forcing hackery such as the examples above, is really discouraging to wider adoption of the pipeline DSL.

in scripted pipeline, it is possible to write :

 
node {
  def sbtHome = tool 'sbt-0.13.15'
  def sbt = "${sbtHome}/bin/sbt -no-colors -batch"
  stage('build') {
    sh "${sbt} clean assembly"

...

 I'm just going to make some experiments with declarative pipelines...

OK I've found a way to use sbt within declarative pipelines :

https://gist.github.com/dacr/a2576dee980c5c9bd29cf538a093ca72

 But it won't work with docker agent for example  as the sbt auto-installation feature is not available in the declarative pipeline context...

FYI, the tool auto-install doesn't work in docker.image.inside whether in Declarative or Scripted. Anyway, this needs the sbt plugin to add a @Symbol.

Here's what I do in declarative mode:

pipeline {
    ...
    environment {
      SBT_HOME = tool name: 'sbt.13.13', type: 'org.jvnet.hudson.plugins.SbtPluginBuilder$SbtInstallation'
      PATH = "${env.SBT_HOME}/bin:${env.PATH}"
    }
    ...
}

A call to sbt can be as simple as

sh 'sbt test'

I'm able to utilize sbt in a declarative pipeline pulling a docker image of sbt from the public registry (https://hub.docker.com/r/hseeberger/scala-sbt/) as the agent: 

pipeline {
    agent {
        docker {
            image 'hseeberger/scala-sbt'
        }
    }
    stages {
        stage('Test') {
            steps {
                echo 'Building..'
                sh "sbt test"
            }
        }
    } 
}

I can confirm that sbt is able to be used as willis6 demonstrates above.