L0 takes protocol bytes off the wire and turns them into typed in-memory values, or serializes outbound requests against the published schemas. Symmetric on both sides — same primitives, mirrored direction.Documentation Index
Fetch the complete documentation index at: https://docs.adcontextprotocol.org/llms.txt
Use this file to discover all available pages before exploring further.
What an SDK at L0 must provide
If you’re picking an SDK or porting one to a new language, this is the L0 build target:- Generated language-native types from the published JSON schemas (one type per request/response pair, plus shared resource types).
- A schema validator wired against the bundled schemas — so adopters can validate inbound and outbound payloads without hand-rolling the schema-loading dance.
- Transport adapters for at least one of {MCP, A2A}; ideally both. These typically wrap upstream protocol SDKs rather than reimplementing them.
- A schema-bundle accessor that finds the right schema files for the active AdCP version without forcing the adopter to hardcode paths.
Pages in this layer
- Schemas — schema bundle, supply-chain verification, type generation, version pinning.
- MCP guide —
tools/callenvelope, JSON-RPC 2.0, transport adapter shape. - A2A guide — SSE event streams, task framing, artifact extraction.
- A2A response format — A2A wire-format reference.
- MCP response extraction — parsing
tools/callresponses to typed values. - A2A response extraction — parsing A2A streams and artifacts.