| Term | What it is |
|---|---|
| Personal access token | The credential for the REST API, the vf CLI and the MCP server. One token, three surfaces. |
| Session key | A separate credential, from the start-session endpoint, used only by /v4/interact. Passing an API key there returns 401. |
| Trace | One item in an agent’s reply: text, a card, a debug note. A turn returns an array of them. |
| CLI | vf, the command-line client. Generated from the same OpenAPI spec as the REST API. |
| MCP server | A Model Context Protocol server whose tools an agent can call. Its tools are populated by syncing the server, not created by hand. |
| Conversation state | The stored state of a live conversation: where it stands and what its variables hold. Separate from the transcript, which is the record. |
| MCP tool | A tool an MCP server advertises. Populated by syncing the server rather than created by hand, so the list mirrors what the server exposes. |
Developer surfaces
Tokens, traces, the CLI and MCP: the vocabulary for driving Voiceflow over HTTP, including the one credential that is not the others.