diff --git a/common/lib/capa/capa_problem.py b/common/lib/capa/capa_problem.py
index a817433b49..fae8042eff 100644
--- a/common/lib/capa/capa_problem.py
+++ b/common/lib/capa/capa_problem.py
@@ -174,10 +174,9 @@ class LoncapaProblem(object):
         return self.correct_map
 
     def get_question_answers(self):
-        '''
-        Make a dict of (id,correct_answer) entries, for all the problems. 
-        Called by "show answers" button JSON request (see capa_module)
-        '''
+        """Returns a dict of answer_ids to answer values. If we can't generate
+        an answer (because it's a customresponse type), that answer_id is 
+        not included."""
         context=self.extract_context(self.tree)
         answer_map = dict()
         problems_simple = self.extract_problems(self.tree)	# purified (flat) XML tree of just response queries
diff --git a/common/lib/capa/checker.py b/common/lib/capa/checker.py
new file mode 100755
index 0000000000..5e0bd34211
--- /dev/null
+++ b/common/lib/capa/checker.py
@@ -0,0 +1,91 @@
+#!/usr/bin/env python
+"""
+Commandline tool for doing operations on Problems
+"""
+import argparse
+import logging
+import sys
+
+from cStringIO import StringIO
+
+from capa_problem import LoncapaProblem
+
+logging.basicConfig(format="%(levelname)s %(message)s")
+log = logging.getLogger('capa.checker')
+
+def main():
+    parser = argparse.ArgumentParser(description='Check Problem Files')
+    parser.add_argument("command", choices=['test']) # Watch? Render? Open?
+    parser.add_argument("files", nargs="+", type=argparse.FileType('r'))
+    parser.add_argument("--seed", required=False, type=int)
+
+    args = parser.parse_args()
+    log.setLevel(logging.INFO)
+
+    old_stdout = sys.stdout
+    old_stderr = sys.stderr
+    for problem_file in args.files:
+        log.info("Opening {0}".format(problem_file.name))
+        sys.stdout = problem_stdout = StringIO()
+        sys.stderr = problem_stderr = StringIO()
+
+        try:
+            problem = LoncapaProblem(problem_file.name, "fakeid", seed=args.seed)
+        except Exception as ex:
+            log.error("Could not parse file {0}".format(problem_file.name))
+            log.exception(ex)
+            continue
+
+        if args.command == 'test':
+            test_problem(problem)
+
+        log_captured_output(problem_stdout, 
+                            "captured stdout from {0}".format(problem_file.name))
+        log_captured_output(problem_stderr,
+                            "captured stderr from {0}".format(problem_file.name))
+
+        # Print captured problem prints
+        problem_file.close()
+
+    sys.stdout = old_stdout
+    sys.stderr = old_stderr
+
+    # In case we want to do anything else here.
+
+def log_captured_output(output_stream, stream_name):
+    output_stream.seek(0)
+    output_text = output_stream.read()
+    if output_text:
+        log.info("##### Begin {0} #####\n".format(stream_name) + output_text)
+        log.info("##### End {0} #####".format(stream_name))
+
+def test_problem(problem):
+    """Split this up so that we're only used for formula/numeric answers.
+
+    Examples of where this fails:
+    * Displayed answers use units but acceptable ones do not.
+      - L1e0.xml
+      - Presents itself as UndefinedVariable (when it tries to pass to calc)
+    * "a or d" is what's displayed, but only "a" or "d" is accepted, not the 
+      string "a or d".
+      - L1-e00.xml
+    """
+    answers = problem.get_question_answers()
+    log.debug(answers)
+    if answers:
+        try:
+            results = problem.grade_answers(answers)
+            log.debug(results)
+            assert(all(result == 'correct' for result in results.values()))
+        except AssertionError:
+            log.error("The following generated answers were not accepted:")
+            for question_id, result in sorted(results.items()):
+                if result != 'correct':
+                    log.error("  {0} = {1}".format(question_id, answers[question_id]))
+        except Exception as ex:
+            log.exception(ex)
+
+
+
+if __name__ == '__main__':
+    sys.exit(main())