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API and protocol reference

Use these pages to look up frame fields, callback signatures, error codes, catalog values and MCP tools. For task-oriented guidance, start with Build an agent or Improve the agent.

PageWhat it holds
The Brain APIEvery callback, its signature, and what it is handed.
The wireEvery frame the two ends send, and what each obliges.
The RTVI planeThe message whitelist, both directions.
Voice and languageThe voices, the languages, and the pairing rule.
Error codesEvery code, what raised it, and whether it ends the call.
The management APIThe programmatic management boundary and session-start route.
The MCP serverThe tools an agent gets, and what each one reads or writes.

Contract lists and stable product claims are checked against their sources.

  • The Voice and Language enums are read out of the proto descriptor by the SDK rather than written down twice, and a test fails if the two drift.
  • Every number, version and count on this site lives once in a facts file next to the source it was read out of, and a checker re-reads each one from that source on every run. A page may also declare the sentences that are wrong because of it, and those are searched for in the prose.
  • The technical nouns come from a closed lexicon, checked the same way, so one concept keeps one word across the proto, the SDK and these pages.

Machine-readable lists are derived where a source exists; explanatory guidance remains in the task pages.