Evaluation of morphology and syntax skills should be included in a full, comprehensive evaluation of speech/language skills.  Here are some things to look for during your evaluation that may indicate difficulty with syntax and morphology:

Morphology and syntax deficits include

• late acquisition of word combinations;
• restricted mean length of utterance (MLU) in morphemes for younger children (although developmental order of morpheme acquisition may be similar to that of typically developing children) and shorter utterances in words for school-age children and adolescents;
• errors occurring most often on verbs (especially verb endings, auxiliary verbs, and past tense marking of regular and irregular forms), function words (e.g., articles and prepositions), and pronouns;
• errors of omission occurring more frequently than errors of misuse, although occurrence of both error types may be inconsistent;
• use of more mature and less mature word forms;
• difficulty comprehending grammatical morphemes, particularly units of short duration (phonetically less salient);
• deficits in morphological awareness (e.g., derivational morphemes, such as prefixes and suffixes, including inflectional morphology, such as plural, present progressive, and past tense markers);
• difficulty judging grammaticality;
• difficulty identifying and correcting grammatical errors;
• difficulty identifying parts of speech;
• problems comprehending and using complex syntactic structures;
• extensive use of simple, non-subordinated utterances in narratives;
• use of subordinating clauses of the earlier developing types, when complex sentences are used;
• difficulty with curriculum-related expository discourse production;
• difficulty decoding (comprehending) morphologically complex words that are common in various academic subjects.

Source: https://www.asha.org/practice-portal/clinical-topics/spoken-language-disorders/#collapse_2

Here are some additional resources when it comes to evaluating this condition: