I would consider a note deficient if there was no assessment and plan documented, and would return it to the provider to be completed. Even if there is no plan, the provider should at least document an impression and state that no treatment or changes in treatment are necessary.
For reference material, take a look at the 1995 E&M guidelines from CMS, section II 'General Principles of Medical Record Documentation':
"1. The medical record should be complete and legible.
2. The documentation of each patient encounter should include: reason for the encounter and relevant history, physical examination findings, and prior diagnostic test results; assessment, clinical impression, or diagnosis; plan for care; and date and legible identity of the observer.
3. If not documented, the rationale for ordering diagnostic and other ancillary services should be easily inferred.
4. Past and present diagnoses should be accessible to the treating and/or consulting physician.
5. Appropriate health risk factors should be identified.
6. The patient's progress, response to and changes in treatment, and revision of diagnosis should be documented."
and in the section on Medical Decision Making:
"For each encounter, an assessment, clinical impression, or diagnosis should be documented. It may be explicitly stated or implied in documented decisions regarding management plans and/or further evaluation.
For a presenting problem with an established diagnosis the record should reflect whether the problem is: a) improved, well controlled, resolving or resolved; or, b) inadequately controlled, worsening, or failing to change as expected.
For a presenting problem without an established diagnosis, the assessment or clinical impression may be stated in the form of a differential diagnoses or as "possible,” "probable,” or "rule out” (R/O) diagnoses.
The initiation of, or changes in, treatment should be documented. Treatment includes a wide range of management options including patient instructions, nursing instructions, therapies, and medications.
If referrals are made, consultations requested or advice sought, the record should indicate to whom or where the referral or consultation is made or from whom the advice is requested."