rohitg00/ai-engineering-from-scratch · error · McpError

-32602

-32602

Error message

missing request _meta

What it means

Error "missing request _meta" thrown in rohitg00/ai-engineering-from-scratch.

Source

Thrown at phases/13-tools-and-protocols/11-mcp-sampling/code/main.py:81

    return {
        PROTOCOL_META: PROTOCOL_VERSION,
        CAPABILITIES_META: capabilities,
        CLIENT_INFO_META: {"name": "lesson-client", "version": "1.0.0"},
    }


def _server_meta() -> dict[str, Any]:
    return {SERVER_INFO_META: {"name": "mrtr-demo", "version": "1.0.0"}}


def complete(**fields: Any) -> dict[str, Any]:
    return {"resultType": "complete", **fields, "_meta": _server_meta()}


def validate_request_meta(params: dict[str, Any]) -> dict[str, Any]:
    meta = params.get("_meta")
    if not isinstance(meta, dict):
        raise McpError(-32602, "missing request _meta")
    requested_version = meta.get(PROTOCOL_META)
    if not isinstance(requested_version, str):
        raise McpError(-32602, "missing protocol version")
    if requested_version != PROTOCOL_VERSION:
        raise McpError(
            -32022,
            "unsupported protocol version",
            {"supported": [PROTOCOL_VERSION], "requested": requested_version},
        )
    capabilities = meta.get(CAPABILITIES_META)
    if not isinstance(capabilities, dict):
        raise McpError(-32602, "missing client capabilities")
    return meta


def server_discover(params: dict[str, Any]) -> dict[str, Any]:
    validate_request_meta(params)
    return complete(

View on GitHub (pinned to 39ea8a1c6d)

When it happens

Trigger: Thrown at phases/13-tools-and-protocols/11-mcp-sampling/code/main.py:81 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of rohitg00/ai-engineering-from-scratch@39ea8a1c6d (2026-08-26). Data as JSON: /api/errors/72bb94a1a8a99235. Report an issue: GitHub.