{"protocolVersion":"0.3.0","name":"ONCE","description":"ONCE is a music distribution agent. It takes a release — audio, cover art, and metadata — validates it against store requirements, delivers it to Spotify, Apple Music, and every other major streaming platform, and reports streams and royalties back. This A2A interface serves public reference data; submitting a release runs over the OAuth-protected MCP server or REST API.","version":"1.0.0","documentationUrl":"https://docs.once.app/mcp","iconUrl":"https://beta.once.app/once_icon.svg","provider":{"organization":"ONCE","url":"https://once.app"},"supportedInterfaces":[{"url":"https://beta.once.app/api/a2a","transport":"JSONRPC"}],"url":"https://beta.once.app/api/a2a","preferredTransport":"JSONRPC","additionalInterfaces":[{"url":"https://beta.once.app/api/a2a","transport":"JSONRPC"}],"capabilities":{"streaming":false,"pushNotifications":false,"stateTransitionHistory":false},"defaultInputModes":["text/plain"],"defaultOutputModes":["text/plain","text/markdown","application/json"],"skills":[{"id":"pricing-lookup","name":"Look up ONCE pricing","description":"Returns what it costs to distribute a release: the per-credit price, the per-song cost for human-made and AI-flagged tracks, bulk bundle discounts, the optional Token Offset add-on, and how auto-reload works.","tags":["pricing","credits","billing"],"examples":["How much does it cost to release a 5-track EP on ONCE?","What is the discount on the largest credit bundle?"]},{"id":"store-catalog","name":"List distribution stores","description":"Returns every store ONCE delivers to, with the numeric store IDs used in `release.distribution_store_ids`, which stores are on by default, and which are partner-only.","tags":["stores","dsp","distribution"],"examples":["Which stores does ONCE distribute to?","What is the store ID for Apple Music?"]},{"id":"metadata-rules","name":"Get release metadata rules","description":"Returns the metadata policy hitlist — the store-side naming, credit, and formatting rules that cause most release rejections. Read this before collecting metadata from a user.","tags":["metadata","validation","policy"],"examples":["What are the rules for featuring artists in a track title?","How should remix credits be formatted?"],"outputModes":["text/markdown","application/json"]},{"id":"submission-handoff","name":"Explain how to submit a release","description":"Explains how a calling agent authenticates and submits a release. Submission itself runs over the OAuth-protected MCP server or REST API, not over A2A, because it charges credits and publishes music on a user's behalf; this skill returns the endpoints, the auth flow, and the required payload shape.","tags":["auth","submission","handoff"],"examples":["How do I submit a release to ONCE from my agent?","What authentication does the ONCE MCP server use?"]}],"securitySchemes":{},"security":[],"additionalDocumentation":{"restApi":"https://docs.once.app/rest-api","mcpServerCard":"https://beta.once.app/.well-known/mcp/server-card.json","apiCatalog":"https://beta.once.app/.well-known/api-catalog","agentAuth":"https://beta.once.app/auth.md"}}