firefly-cli is a command-line tool that lets an LLM agent (and you) interact with a self-hosted Firefly III instance over its REST API. It exposes the 'firefly' command, emits JSON by default (pass --human for tables), and resolves account, category, and tag names to IDs. Pure Python, standard library only. No third-party runtime dependencies. Requires Python 3.11 or newer. Configuration: provide your Firefly III URL and a personal access token either by running 'firefly auth set' (stored in a local TOML file) or by setting the FIREFLY_URL and FIREFLY_TOKEN environment variables, which take precedence over the config file. A Firefly III instance and a valid personal access token are required at runtime; they are not build-time dependencies.