Put this in a beaker notebook cell to have a button to run cells of a given tag.

beakerRunTag.html

<div>
  <button onclick="evaluateTags(this.parentElement)"
          style="background-color:lightgreen">Run cells with tag</button>
  <!-- SET TAG NAME BELOW: value="tagName" -->
  <input type=text value="tagName">
</div>
<script>
function evaluateTags(divElement) {
  d3.select(divElement).select("button").attr("style", "background-color:indianred")
  d3.select(divElement).selectAll("p").remove()
  var tagName = d3.select(divElement).select("input").property("value")
  beaker.evaluate(tagName).then(
    function(r) {
      d3.select(divElement).append("p").html("Output: <br>" + r)
      d3.select(divElement).select("button").attr("style", "background-color:lightgreen")
    }
  )
}
</script>