{"slug":"gandalf-the-grader","name":"Gandalf the Grader","ownerSlug":"handshake","artifactType":"Verifier","availabilityKind":"public-sample","access":["Public / Open","Open source"],"summary":"An open-source reactive agent-as-judge that inspects files and environment state while grading agent work.","description":"Gandalf runs inside a rollout environment and chooses what evidence to inspect using available tools. Handshake reports results on BankerVerifierBench and an internal productivity benchmark; those performance claims remain company-reported unless independently reproduced.","domains":["finance","enterprise","tool-use"],"capabilities":{"tool-use":"yes","stateful":"yes","file-manipulation":"yes","human-in-the-loop":"yes"},"verifierType":"Reactive agent-as-judge","firstReleased":"2026-05-27","lastVerified":"2026-08-16","verificationStatus":"confirmed","confidence":"high","links":[{"label":"Technical article","url":"https://joinhandshake.com/research/ai/gandalf-the-grader/","kind":"official"},{"label":"Source code","url":"https://github.com/Handshake-AI-Research/gandalf-the-grader","kind":"github"}],"sourceIds":["handshake-gandalf","handshake-gandalf-github"],"relatedArtifactSlugs":["bankertoolbench"],"canonicalUrl":"https://envindex.com/environments/gandalf-the-grader","owner":{"slug":"handshake","name":"Handshake","website":"https://joinhandshake.com/research/ai","tagline":"Career network turned human-data and RL environments provider via Handshake AI","description":"Handshake operates the largest early-career network in the US and launched Handshake AI, a human data labs business that recruits PhD-level experts to build evals and RL environments for frontier AI labs. It leverages its network of millions of students and experts for domain-specific data.","domains":["multi-domain","data-labeling","rlhf"],"locations":["San Francisco","New York","Bangalore","Berlin"],"founders":[{"name":"Garrett Lord","xHandle":null}],"teamSize":"250+","funding":"Series F, $200M (2022, ~$3.5B valuation)","raising":null,"founded":2014,"notable":"Known for its 'Gandalf the Grader' benchmark work"},"sources":[{"id":"handshake-gandalf","url":"https://joinhandshake.com/research/ai/gandalf-the-grader/","title":"Your verifier is probably the bottleneck. We built one that isn’t.","publisher":"Handshake AI Research","sourceType":"official","publishedAt":"2026-05-27","accessedAt":"2026-08-16","verificationStatus":"company-reported"},{"id":"handshake-gandalf-github","url":"https://github.com/Handshake-AI-Research/gandalf-the-grader","title":"Gandalf the Grader source repository","publisher":"Handshake AI Research","sourceType":"repository","accessedAt":"2026-08-16","verificationStatus":"confirmed"}]}