{"slug":"legion-elixir","name":"Legion","vendor":"Software Mansion","tagline":"Elixir runtime for agents that live inside your app and do work by writing sandboxed Lua or Elixir instead of calling tools one at a time","url":"https://agentboards.org/agent/legion-elixir","website":"https://hexdocs.pm/legion/Legion.html","docs":"https://hexdocs.pm/legion","repo":"https://github.com/software-mansion-labs/legion","category":"framework","execution":["local"],"license":"MIT","open_source":true,"pricing":{"model":"byok","summary":"Free and open source under MIT; you pay the model provider you configure\n","from_usd":0,"free_tier":true,"byok":true},"models":{"backbone":["multiple providers"],"bring_your_own_model":true,"local_models":false},"protocols":{"mcp_client":false,"mcp_server":false,"openapi":false},"capabilities":{"terminal_exec":false,"browser":false,"multi_file_edit":true,"git_ops":false,"docker_sandbox":true,"multi_agent":false,"headless_ci":false},"context_window":null,"platforms":["macos","linux"],"install":[{"label":"Hex","command":"add {:legion, \"~> 0.1\"} to mix.exs deps"}],"benchmarks":[],"tags":["open-source","elixir","framework","code-execution","sandbox"],"github_stars":220,"metrics":{"stars":220,"pushed_at":"2026-10-01T10:42:57Z","archived":false,"open_issues":1,"latest_version":"v0.5.1","latest_version_at":"2026-09-26T08:38:29Z","latest_version_url":"https://github.com/software-mansion/legion/releases/tag/v0.5.1","version_source":"github","checked_at":"2026-10-02T05:01:10.570Z"},"sources":{"overview":"https://github.com/software-mansion-labs/legion","capabilities":"https://github.com/software-mansion-labs/legion","models":"https://github.com/software-mansion-labs/legion","license":"https://github.com/software-mansion-labs/legion","install":"https://hex.pm/packages/legion","docs":"https://hexdocs.pm/legion"},"verified_at":"2026-09-04","adoption":{"score":2.7,"signals":{"github_stars":217,"hn_mentions_1y":20},"measured_at":"2026-09-28"},"scores":{"panel":6.5,"adoption":2.7,"spread":2.3,"facts":6.7,"board":6,"dimensions":{"reliability":6,"usefulness":6.2,"cost":8,"longevity":5.8},"per_persona":{"amigo":6.8,"critico":6,"profesor":7.8,"inversora":6.3,"jefa":5.5,"hacker":6.8},"community":null},"rank":null,"category_rank":44,"panel_reviews":[{"persona":"juez","persona_name":"El Juez","ai_generated":true,"verdict":"El Profesor calls the execution model the best idea on this row and El Crítico calls the same model the reason to be careful. Both are describing generated code that runs.","scores":null,"evidence":[]},{"persona":"amigo","persona_name":"El Amigo","ai_generated":true,"verdict":"Pick Legion if you write Elixir and want the agent inside the application rather than beside it; pick a framework in Python if the rest of your stack already lives there.","scores":{"reliability":6,"usefulness":7,"cost":8,"longevity":6},"evidence":["https://github.com/software-mansion-labs/legion","https://hexdocs.pm/legion"]},{"persona":"critico","persona_name":"El Crítico","ai_generated":true,"verdict":"The generated snippet runs in the project's own sandbox, and the README does not describe a container runtime, so the isolation boundary is whatever the host process could already reach.","scores":{"reliability":5,"usefulness":6,"cost":7,"longevity":6},"evidence":["https://github.com/software-mansion-labs/legion"]},{"persona":"profesor","persona_name":"El Profesor","ai_generated":true,"verdict":"One evaluation can filter, branch and loop, so a sequence that costs a tool-calling agent a model round trip per step collapses into a single call. The claim is structural and checkable.","scores":{"reliability":7,"usefulness":8,"cost":9,"longevity":7},"evidence":["https://github.com/software-mansion-labs/legion","https://hexdocs.pm/legion"]},{"persona":"inversora","persona_name":"La Inversora","ai_generated":true,"verdict":"166 stars and a consultancy's name on it. Software Mansion builds open libraries to sell engineering time, which funds this exactly as long as the pitch still works.","scores":{"reliability":6,"usefulness":6,"cost":8,"longevity":5},"evidence":["https://github.com/software-mansion-labs/legion"]},{"persona":"jefa","persona_name":"La Jefa","ai_generated":true,"verdict":"Nothing to license and nothing to govern: this is a Hex dependency my engineers add to a mix file, so what I am approving is a service my own team will operate.","scores":{"reliability":5,"usefulness":4,"cost":8,"longevity":5},"evidence":["https://github.com/software-mansion-labs/legion","https://hex.pm/packages/legion"]},{"persona":"hacker","persona_name":"El Hacker","ai_generated":true,"verdict":"MIT and a single Hex dependency, so the whole thing is readable in an afternoon. There is no MCP client, so the tools are the modules I hand it and nothing else.","scores":{"reliability":7,"usefulness":6,"cost":8,"longevity":6},"evidence":["https://github.com/software-mansion-labs/legion","https://hexdocs.pm/legion"]},{"persona":"comediante","persona_name":"El Comediante","ai_generated":true,"verdict":"It writes Lua to get work done in Elixir, which is two functional languages agreeing that a third one should take the blame.","scores":null,"evidence":[]}]}