Dependency specification Dependencies for a project can be specified in various forms, which depend on the type of the dependency and on the optional constraints that might be needed for it to be installed. project.dependencies and tool.poetry.dependencies Prior Poetry 2.0, dependencies had to be declared in the tool.poetry.dependencies section of the pyproject.toml file. [tool.poetry.dependencies] requests = "^2.13.0" With Poetry 2.0, you should consider using the project.dependencies section instead. [project] # ... dependencies = [ "requests (>=2.23.0,<3.0.0)" ] While dependencies in tool.poetry.dependencies are specified using toml tables, dependencies in project.dependencies are specified as strings according to PEP 508.