Course syllabi are a required component of college and university courses. Syllabi present both broader course structuring practices, are a valuable "first impression" of what instructors want to offer their students, and are used as tools in course design. While best teaching practices suggest specific recommendations for syllabi development, there is little research evidence regarding their structure and use, especially in the context of introductory physics for life sciences (IPLS) courses. IPLS courses typically host students pursuing careers in the biological or health-related sciences, which are rapidly growing majors compared to other STEM degrees. Since few of these students have significant previous experience with physics, the course syllabus provides a first framing and establishment of expectations for them. In this paper, we analyzed how IPLS instructors write syllabi, how they use them in the course design process, and what experienced instructors recommend to be included in the syllabi. Furthermore, based on these analyses we compiled a set of 31 key components (organized in seven categories) for IPLS course syllabi supported by both widespread use and recommendations from experienced practitioners. We present these components and discuss implications for IPLS syllabus design. Specifically, we bring attention to the value of explicitly incorporating interdisciplinary language in syllabi narratives and learning objectives. This work provides guidance for IPLS course and syllabus design, and can also be relevant for modern interdisciplinary courses with features similar to IPLS courses.