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Per-version method maps and parse/serialize functions for MCP traffic.

This module is supported public API; the mcp.types.v* packages it draws on are internal validators and not for direct import.

Surface maps key (method, version) to per-version wire types (key absence is the version gate; shape validation is per schema era, i.e. 2025-11-25 for every pre-2026 version and 2026-07-28 for 2026). Monolith maps key method to the version-free mcp.types models user code receives.

SERVER_RESULTS module-attribute 

SERVER_RESULTS: Final[
    Mapping[tuple[str, str], type[BaseModel] | UnionType]
] = MappingProxyType(
    {
        (
            "completion/complete",
            "2024-11-05",
        ): CompleteResult,
        ("initialize", "2024-11-05"): InitializeResult,
        ("logging/setLevel", "2024-11-05"): EmptyResult,
        ("ping", "2024-11-05"): EmptyResult,
        ("prompts/get", "2024-11-05"): GetPromptResult,
        ("prompts/list", "2024-11-05"): ListPromptsResult,
        (
            "resources/list",
            "2024-11-05",
        ): ListResourcesResult,
        (
            "resources/read",
            "2024-11-05",
        ): ReadResourceResult,
        ("resources/subscribe", "2024-11-05"): EmptyResult,
        (
            "resources/templates/list",
            "2024-11-05",
        ): ListResourceTemplatesResult,
        (
            "resources/unsubscribe",
            "2024-11-05",
        ): EmptyResult,
        ("tools/call", "2024-11-05"): CallToolResult,
        ("tools/list", "2024-11-05"): ListToolsResult,
        (
            "completion/complete",
            "2025-03-26",
        ): CompleteResult,
        ("initialize", "2025-03-26"): InitializeResult,
        ("logging/setLevel", "2025-03-26"): EmptyResult,
        ("ping", "2025-03-26"): EmptyResult,
        ("prompts/get", "2025-03-26"): GetPromptResult,
        ("prompts/list", "2025-03-26"): ListPromptsResult,
        (
            "resources/list",
            "2025-03-26",
        ): ListResourcesResult,
        (
            "resources/read",
            "2025-03-26",
        ): ReadResourceResult,
        ("resources/subscribe", "2025-03-26"): EmptyResult,
        (
            "resources/templates/list",
            "2025-03-26",
        ): ListResourceTemplatesResult,
        (
            "resources/unsubscribe",
            "2025-03-26",
        ): EmptyResult,
        ("tools/call", "2025-03-26"): CallToolResult,
        ("tools/list", "2025-03-26"): ListToolsResult,
        (
            "completion/complete",
            "2025-06-18",
        ): CompleteResult,
        ("initialize", "2025-06-18"): InitializeResult,
        ("logging/setLevel", "2025-06-18"): EmptyResult,
        ("ping", "2025-06-18"): EmptyResult,
        ("prompts/get", "2025-06-18"): GetPromptResult,
        ("prompts/list", "2025-06-18"): ListPromptsResult,
        (
            "resources/list",
            "2025-06-18",
        ): ListResourcesResult,
        (
            "resources/read",
            "2025-06-18",
        ): ReadResourceResult,
        ("resources/subscribe", "2025-06-18"): EmptyResult,
        (
            "resources/templates/list",
            "2025-06-18",
        ): ListResourceTemplatesResult,
        (
            "resources/unsubscribe",
            "2025-06-18",
        ): EmptyResult,
        ("tools/call", "2025-06-18"): CallToolResult,
        ("tools/list", "2025-06-18"): ListToolsResult,
        (
            "completion/complete",
            "2025-11-25",
        ): CompleteResult,
        ("initialize", "2025-11-25"): InitializeResult,
        ("logging/setLevel", "2025-11-25"): EmptyResult,
        ("ping", "2025-11-25"): EmptyResult,
        ("prompts/get", "2025-11-25"): GetPromptResult,
        ("prompts/list", "2025-11-25"): ListPromptsResult,
        (
            "resources/list",
            "2025-11-25",
        ): ListResourcesResult,
        (
            "resources/read",
            "2025-11-25",
        ): ReadResourceResult,
        ("resources/subscribe", "2025-11-25"): EmptyResult,
        (
            "resources/templates/list",
            "2025-11-25",
        ): ListResourceTemplatesResult,
        (
            "resources/unsubscribe",
            "2025-11-25",
        ): EmptyResult,
        ("tools/call", "2025-11-25"): CallToolResult,
        ("tools/list", "2025-11-25"): ListToolsResult,
        (
            "completion/complete",
            "2026-07-28",
        ): CompleteResult,
        ("prompts/get", "2026-07-28"): AnyGetPromptResult,
        ("prompts/list", "2026-07-28"): ListPromptsResult,
        (
            "resources/list",
            "2026-07-28",
        ): ListResourcesResult,
        (
            "resources/read",
            "2026-07-28",
        ): AnyReadResourceResult,
        (
            "resources/templates/list",
            "2026-07-28",
        ): ListResourceTemplatesResult,
        ("server/discover", "2026-07-28"): DiscoverResult,
        ("subscriptions/listen", "2026-07-28"): EmptyResult,
        ("tools/call", "2026-07-28"): AnyCallToolResult,
        ("tools/list", "2026-07-28"): ListToolsResult,
    }
)

Results servers send, keyed by the originating client request's (method, version).

CLIENT_RESULTS module-attribute 

CLIENT_RESULTS: Final[
    Mapping[tuple[str, str], type[BaseModel] | UnionType]
] = MappingProxyType(
    {
        ("ping", "2024-11-05"): EmptyResult,
        ("roots/list", "2024-11-05"): ListRootsResult,
        (
            "sampling/createMessage",
            "2024-11-05",
        ): CreateMessageResult,
        ("ping", "2025-03-26"): EmptyResult,
        ("roots/list", "2025-03-26"): ListRootsResult,
        (
            "sampling/createMessage",
            "2025-03-26",
        ): CreateMessageResult,
        ("elicitation/create", "2025-06-18"): ElicitResult,
        ("ping", "2025-06-18"): EmptyResult,
        ("roots/list", "2025-06-18"): ListRootsResult,
        (
            "sampling/createMessage",
            "2025-06-18",
        ): CreateMessageResult,
        ("elicitation/create", "2025-11-25"): ElicitResult,
        ("ping", "2025-11-25"): EmptyResult,
        ("roots/list", "2025-11-25"): ListRootsResult,
        (
            "sampling/createMessage",
            "2025-11-25",
        ): CreateMessageResult,
    }
)

Results clients send, keyed by the originating server request's (method, version).

SPEC_CLIENT_METHODS module-attribute 

SPEC_CLIENT_METHODS: Final[frozenset[str]] = frozenset(
    m for (m, _) in CLIENT_REQUESTS
)

Spec request methods a client may send (any version); the server-side spec-method discriminator.

SPEC_CLIENT_NOTIFICATION_METHODS module-attribute 

SPEC_CLIENT_NOTIFICATION_METHODS: Final[frozenset[str]] = (
    frozenset(m for (m, _) in CLIENT_NOTIFICATIONS)
)

Spec notification methods a client may send (any version); the server-side spec-method discriminator.

MONOLITH_REQUESTS module-attribute 

MONOLITH_REQUESTS: Final[
    Mapping[str, type[Request[Any, Any]]]
] = MappingProxyType(
    {
        "completion/complete": CompleteRequest,
        "elicitation/create": ElicitRequest,
        "initialize": InitializeRequest,
        "logging/setLevel": SetLevelRequest,
        "ping": PingRequest,
        "prompts/get": GetPromptRequest,
        "prompts/list": ListPromptsRequest,
        "resources/list": ListResourcesRequest,
        "resources/read": ReadResourceRequest,
        "resources/subscribe": SubscribeRequest,
        "resources/templates/list": ListResourceTemplatesRequest,
        "resources/unsubscribe": UnsubscribeRequest,
        "roots/list": ListRootsRequest,
        "sampling/createMessage": CreateMessageRequest,
        "server/discover": DiscoverRequest,
        "subscriptions/listen": SubscriptionsListenRequest,
        "tools/call": CallToolRequest,
        "tools/list": ListToolsRequest,
    }
)

Monolith request model per method, both directions.

MONOLITH_NOTIFICATIONS module-attribute 

MONOLITH_NOTIFICATIONS: Final[
    Mapping[str, type[Notification[Any, Any]]]
] = MappingProxyType(
    {
        "notifications/cancelled": CancelledNotification,
        "notifications/elicitation/complete": ElicitCompleteNotification,
        "notifications/initialized": InitializedNotification,
        "notifications/message": LoggingMessageNotification,
        "notifications/progress": ProgressNotification,
        "notifications/prompts/list_changed": PromptListChangedNotification,
        "notifications/resources/list_changed": ResourceListChangedNotification,
        "notifications/resources/updated": ResourceUpdatedNotification,
        "notifications/roots/list_changed": RootsListChangedNotification,
        "notifications/subscriptions/acknowledged": SubscriptionsAcknowledgedNotification,
        "notifications/tools/list_changed": ToolListChangedNotification,
    }
)

Monolith notification model per method, both directions.

MONOLITH_RESULTS module-attribute 

MONOLITH_RESULTS: Final[
    Mapping[str, type[Result] | UnionType]
] = MappingProxyType(
    {
        "completion/complete": CompleteResult,
        "elicitation/create": ElicitResult,
        "initialize": InitializeResult,
        "logging/setLevel": EmptyResult,
        "ping": EmptyResult,
        "prompts/get": GetPromptResult
        | InputRequiredResult,
        "prompts/list": ListPromptsResult,
        "resources/list": ListResourcesResult,
        "resources/read": ReadResourceResult
        | InputRequiredResult,
        "resources/subscribe": EmptyResult,
        "resources/templates/list": ListResourceTemplatesResult,
        "resources/unsubscribe": EmptyResult,
        "roots/list": ListRootsResult,
        "sampling/createMessage": CreateMessageResult
        | CreateMessageResultWithTools,
        "server/discover": DiscoverResult,
        "subscriptions/listen": EmptyResult,
        "tools/call": CallToolResult | InputRequiredResult,
        "tools/list": ListToolsResult,
    }
)

Monolith result model (or two-arm union) per request method.

validate_client_request 

validate_client_request(
    method: str,
    version: str,
    params: Mapping[str, Any] | None,
    *,
    surface: Mapping[
        tuple[str, str], type[BaseModel]
    ] = CLIENT_REQUESTS
) -> None

Validate a client request against surface only.

Raises:

Type Description
ValueError

version is not a known protocol version.
KeyError

(method, version) is not in surface (the version gate).
ValidationError

body fails surface validation.
Source code in src/mcp/types/methods.py 
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def validate_client_request(
    method: str,
    version: str,
    params: Mapping[str, Any] | None,
    *,
    surface: Mapping[tuple[str, str], type[BaseModel]] = CLIENT_REQUESTS,
) -> None:
    """Validate a client request against `surface` only.

    Raises:
        ValueError: `version` is not a known protocol version.
        KeyError: `(method, version)` is not in `surface` (the version gate).
        pydantic.ValidationError: body fails surface validation.
    """
    _check_known_version(version)
    surface[(method, version)].model_validate({**_REQUEST_STUB, **_body(method, params)}, by_name=False)

parse_client_request 

parse_client_request(
    method: str,
    version: str,
    params: Mapping[str, Any] | None,
    *,
    surface: Mapping[
        tuple[str, str], type[BaseModel]
    ] = CLIENT_REQUESTS,
    monolith: Mapping[
        str, type[Request[Any, Any]]
    ] = MONOLITH_REQUESTS
) -> Request[Any, Any]

Validate a client request against surface, then parse and return its monolith model.

Parameters:

Name Type Description Default
surface Mapping[tuple[str, str], type[BaseModel]]

(method, version) to wire-type map; the version-gate lookup and (per-schema-era) shape check run against this. Pass an extended map to admit custom methods.

 CLIENT_REQUESTS
monolith Mapping[str, type[Request[Any, Any]]]

method to version-free model map; the returned instance is parsed from this row. Must cover every method surface admits.

 MONOLITH_REQUESTS

Raises:

Type Description
ValueError

version is not a known protocol version.
KeyError

(method, version) is not in surface (the version gate).
ValidationError

body fails surface or monolith validation.
RuntimeError

surface matched but method has no monolith row.
Source code in src/mcp/types/methods.py 
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def parse_client_request(
    method: str,
    version: str,
    params: Mapping[str, Any] | None,
    *,
    surface: Mapping[tuple[str, str], type[BaseModel]] = CLIENT_REQUESTS,
    monolith: Mapping[str, type[types.Request[Any, Any]]] = MONOLITH_REQUESTS,
) -> types.Request[Any, Any]:
    """Validate a client request against `surface`, then parse and return its `monolith` model.

    Args:
        surface: `(method, version)` to wire-type map; the version-gate lookup
            and (per-schema-era) shape check run against this. Pass an extended
            map to admit custom methods.
        monolith: `method` to version-free model map; the returned instance is
            parsed from this row. Must cover every method `surface` admits.

    Raises:
        ValueError: `version` is not a known protocol version.
        KeyError: `(method, version)` is not in `surface` (the version gate).
        pydantic.ValidationError: body fails surface or monolith validation.
        RuntimeError: surface matched but `method` has no monolith row.
    """
    validate_client_request(method, version, params, surface=surface)
    return _monolith_row(monolith, method).model_validate(_body(method, params), by_name=False)

parse_server_request 

parse_server_request(
    method: str,
    version: str,
    params: Mapping[str, Any] | None,
    *,
    surface: Mapping[
        tuple[str, str], type[BaseModel]
    ] = SERVER_REQUESTS,
    monolith: Mapping[
        str, type[Request[Any, Any]]
    ] = MONOLITH_REQUESTS
) -> Request[Any, Any]

Validate a server request against surface, then parse and return its monolith model.

Parameters:

Name Type Description Default
surface Mapping[tuple[str, str], type[BaseModel]]

(method, version) to wire-type map; the version-gate lookup and (per-schema-era) shape check run against this. Pass an extended map to admit custom methods.

 SERVER_REQUESTS
monolith Mapping[str, type[Request[Any, Any]]]

method to version-free model map; the returned instance is parsed from this row. Must cover every method surface admits.

 MONOLITH_REQUESTS

Raises:

Type Description
ValueError

version is not a known protocol version.
KeyError

(method, version) is not in surface (the version gate).
ValidationError

body fails surface or monolith validation.
RuntimeError

surface matched but method has no monolith row.
Source code in src/mcp/types/methods.py 
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def parse_server_request(
    method: str,
    version: str,
    params: Mapping[str, Any] | None,
    *,
    surface: Mapping[tuple[str, str], type[BaseModel]] = SERVER_REQUESTS,
    monolith: Mapping[str, type[types.Request[Any, Any]]] = MONOLITH_REQUESTS,
) -> types.Request[Any, Any]:
    """Validate a server request against `surface`, then parse and return its `monolith` model.

    Args:
        surface: `(method, version)` to wire-type map; the version-gate lookup
            and (per-schema-era) shape check run against this. Pass an extended
            map to admit custom methods.
        monolith: `method` to version-free model map; the returned instance is
            parsed from this row. Must cover every method `surface` admits.

    Raises:
        ValueError: `version` is not a known protocol version.
        KeyError: `(method, version)` is not in `surface` (the version gate).
        pydantic.ValidationError: body fails surface or monolith validation.
        RuntimeError: surface matched but `method` has no monolith row.
    """
    _check_known_version(version)
    surface_type = surface[(method, version)]
    surface_type.model_validate({**_REQUEST_STUB, **_body(method, params)}, by_name=False)
    return _monolith_row(monolith, method).model_validate(_body(method, params), by_name=False)

validate_client_notification 

validate_client_notification(
    method: str,
    version: str,
    params: Mapping[str, Any] | None,
    *,
    surface: Mapping[
        tuple[str, str], type[BaseModel]
    ] = CLIENT_NOTIFICATIONS
) -> None

Validate a client notification against surface only.

Raises:

Type Description
ValueError

version is not a known protocol version.
KeyError

(method, version) is not in surface.
ValidationError

body fails surface validation.
Source code in src/mcp/types/methods.py 
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def validate_client_notification(
    method: str,
    version: str,
    params: Mapping[str, Any] | None,
    *,
    surface: Mapping[tuple[str, str], type[BaseModel]] = CLIENT_NOTIFICATIONS,
) -> None:
    """Validate a client notification against `surface` only.

    Raises:
        ValueError: `version` is not a known protocol version.
        KeyError: `(method, version)` is not in `surface`.
        pydantic.ValidationError: body fails surface validation.
    """
    _check_known_version(version)
    surface[(method, version)].model_validate({**_NOTIFICATION_STUB, **_body(method, params)}, by_name=False)

parse_client_notification 

parse_client_notification(
    method: str,
    version: str,
    params: Mapping[str, Any] | None,
    *,
    surface: Mapping[
        tuple[str, str], type[BaseModel]
    ] = CLIENT_NOTIFICATIONS,
    monolith: Mapping[
        str, type[Notification[Any, Any]]
    ] = MONOLITH_NOTIFICATIONS
) -> Notification[Any, Any]

Validate a client notification against surface, then parse and return its monolith model.

Parameters:

Name Type Description Default
surface Mapping[tuple[str, str], type[BaseModel]]

(method, version) to wire-type map; the version-gate lookup and (per-schema-era) shape check run against this. Pass an extended map to admit custom methods.

 CLIENT_NOTIFICATIONS
monolith Mapping[str, type[Notification[Any, Any]]]

method to version-free model map; the returned instance is parsed from this row. Must cover every method surface admits.

 MONOLITH_NOTIFICATIONS

Raises:

Type Description
ValueError

version is not a known protocol version.
KeyError

(method, version) is not in surface.
ValidationError

body fails surface or monolith validation.
RuntimeError

surface matched but method has no monolith row.
Source code in src/mcp/types/methods.py 
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def parse_client_notification(
    method: str,
    version: str,
    params: Mapping[str, Any] | None,
    *,
    surface: Mapping[tuple[str, str], type[BaseModel]] = CLIENT_NOTIFICATIONS,
    monolith: Mapping[str, type[types.Notification[Any, Any]]] = MONOLITH_NOTIFICATIONS,
) -> types.Notification[Any, Any]:
    """Validate a client notification against `surface`, then parse and return its `monolith` model.

    Args:
        surface: `(method, version)` to wire-type map; the version-gate lookup
            and (per-schema-era) shape check run against this. Pass an extended
            map to admit custom methods.
        monolith: `method` to version-free model map; the returned instance is
            parsed from this row. Must cover every method `surface` admits.

    Raises:
        ValueError: `version` is not a known protocol version.
        KeyError: `(method, version)` is not in `surface`.
        pydantic.ValidationError: body fails surface or monolith validation.
        RuntimeError: surface matched but `method` has no monolith row.
    """
    validate_client_notification(method, version, params, surface=surface)
    return _monolith_row(monolith, method).model_validate(_body(method, params), by_name=False)

parse_server_notification 

parse_server_notification(
    method: str,
    version: str,
    params: Mapping[str, Any] | None,
    *,
    surface: Mapping[
        tuple[str, str], type[BaseModel]
    ] = SERVER_NOTIFICATIONS,
    monolith: Mapping[
        str, type[Notification[Any, Any]]
    ] = MONOLITH_NOTIFICATIONS
) -> Notification[Any, Any]

Validate a server notification against surface, then parse and return its monolith model.

Parameters:

Name Type Description Default
surface Mapping[tuple[str, str], type[BaseModel]]

(method, version) to wire-type map; the version-gate lookup and (per-schema-era) shape check run against this. Pass an extended map to admit custom methods.

 SERVER_NOTIFICATIONS
monolith Mapping[str, type[Notification[Any, Any]]]

method to version-free model map; the returned instance is parsed from this row. Must cover every method surface admits.

 MONOLITH_NOTIFICATIONS

Raises:

Type Description
ValueError

version is not a known protocol version.
KeyError

(method, version) is not in surface.
ValidationError

body fails surface or monolith validation.
RuntimeError

surface matched but method has no monolith row.
Source code in src/mcp/types/methods.py 
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def parse_server_notification(
    method: str,
    version: str,
    params: Mapping[str, Any] | None,
    *,
    surface: Mapping[tuple[str, str], type[BaseModel]] = SERVER_NOTIFICATIONS,
    monolith: Mapping[str, type[types.Notification[Any, Any]]] = MONOLITH_NOTIFICATIONS,
) -> types.Notification[Any, Any]:
    """Validate a server notification against `surface`, then parse and return its `monolith` model.

    Args:
        surface: `(method, version)` to wire-type map; the version-gate lookup
            and (per-schema-era) shape check run against this. Pass an extended
            map to admit custom methods.
        monolith: `method` to version-free model map; the returned instance is
            parsed from this row. Must cover every method `surface` admits.

    Raises:
        ValueError: `version` is not a known protocol version.
        KeyError: `(method, version)` is not in `surface`.
        pydantic.ValidationError: body fails surface or monolith validation.
        RuntimeError: surface matched but `method` has no monolith row.
    """
    _check_known_version(version)
    surface_type = surface[(method, version)]
    surface_type.model_validate({**_NOTIFICATION_STUB, **_body(method, params)}, by_name=False)
    return _monolith_row(monolith, method).model_validate(_body(method, params), by_name=False)

serialize_server_result 

serialize_server_result(
    method: str,
    version: str,
    data: Mapping[str, Any],
    *,
    surface: Mapping[
        tuple[str, str], type[BaseModel] | UnionType
    ] = SERVER_RESULTS
) -> dict[str, Any]

Validate data against surface and return its surface-shaped dump.

The surface model carries extra="ignore", so fields not in version's schema are dropped from the returned dict.

Raises:

Type Description
ValueError

version is not a known protocol version.
KeyError

(method, version) is not in surface.
ValidationError

result fails surface validation.
Source code in src/mcp/types/methods.py 
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def serialize_server_result(
    method: str,
    version: str,
    data: Mapping[str, Any],
    *,
    surface: Mapping[tuple[str, str], type[BaseModel] | UnionType] = SERVER_RESULTS,
) -> dict[str, Any]:
    """Validate `data` against `surface` and return its surface-shaped dump.

    The surface model carries `extra="ignore"`, so fields not in `version`'s
    schema are dropped from the returned dict.

    Raises:
        ValueError: `version` is not a known protocol version.
        KeyError: `(method, version)` is not in `surface`.
        pydantic.ValidationError: result fails surface validation.
    """
    _check_known_version(version)
    adapter = _adapter(surface[(method, version)])
    return adapter.dump_python(
        adapter.validate_python(data, by_name=False), by_alias=True, mode="json", exclude_none=True
    )

validate_server_result 

validate_server_result(
    method: str,
    version: str,
    data: Mapping[str, Any],
    *,
    surface: Mapping[
        tuple[str, str], type[BaseModel] | UnionType
    ] = SERVER_RESULTS
) -> None

Validate a server result against surface only.

Raises:

Type Description
ValueError

version is not a known protocol version.
KeyError

(method, version) is not in surface.
ValidationError

result fails surface validation.
Source code in src/mcp/types/methods.py 
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def validate_server_result(
    method: str,
    version: str,
    data: Mapping[str, Any],
    *,
    surface: Mapping[tuple[str, str], type[BaseModel] | UnionType] = SERVER_RESULTS,
) -> None:
    """Validate a server result against `surface` only.

    Raises:
        ValueError: `version` is not a known protocol version.
        KeyError: `(method, version)` is not in `surface`.
        pydantic.ValidationError: result fails surface validation.
    """
    serialize_server_result(method, version, data, surface=surface)

parse_server_result 

parse_server_result(
    method: str,
    version: str,
    data: Mapping[str, Any],
    *,
    surface: Mapping[
        tuple[str, str], type[BaseModel] | UnionType
    ] = SERVER_RESULTS,
    monolith: Mapping[
        str, type[Result] | UnionType
    ] = MONOLITH_RESULTS
) -> Result

Validate a server result against surface, then parse and return its monolith model.

Parameters:

Name Type Description Default
surface Mapping[tuple[str, str], type[BaseModel] | UnionType]

(method, version) to wire-type map; the version-gate lookup and (per-schema-era) shape check run against this. Pass an extended map to admit custom methods.

 SERVER_RESULTS
monolith Mapping[str, type[Result] | UnionType]

method to version-free model map; the returned instance is parsed from this row. Must cover every method surface admits.

 MONOLITH_RESULTS

Raises:

Type Description
ValueError

version is not a known protocol version.
KeyError

(method, version) is not in surface.
ValidationError

result fails surface or monolith validation.
RuntimeError

surface matched but method has no monolith row.
Source code in src/mcp/types/methods.py 
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def parse_server_result(
    method: str,
    version: str,
    data: Mapping[str, Any],
    *,
    surface: Mapping[tuple[str, str], type[BaseModel] | UnionType] = SERVER_RESULTS,
    monolith: Mapping[str, type[types.Result] | UnionType] = MONOLITH_RESULTS,
) -> types.Result:
    """Validate a server result against `surface`, then parse and return its `monolith` model.

    Args:
        surface: `(method, version)` to wire-type map; the version-gate lookup
            and (per-schema-era) shape check run against this. Pass an extended
            map to admit custom methods.
        monolith: `method` to version-free model map; the returned instance is
            parsed from this row. Must cover every method `surface` admits.

    Raises:
        ValueError: `version` is not a known protocol version.
        KeyError: `(method, version)` is not in `surface`.
        pydantic.ValidationError: result fails surface or monolith validation.
        RuntimeError: surface matched but `method` has no monolith row.
    """
    validate_server_result(method, version, data, surface=surface)
    result: types.Result = _adapter(_monolith_row(monolith, method)).validate_python(data, by_name=False)
    return result

validate_client_result 

validate_client_result(
    method: str,
    version: str,
    data: Mapping[str, Any],
    *,
    surface: Mapping[
        tuple[str, str], type[BaseModel] | UnionType
    ] = CLIENT_RESULTS
) -> None

Validate a client result against surface only.

Raises:

Type Description
ValueError

version is not a known protocol version.
KeyError

(method, version) is not in surface.
ValidationError

result fails surface validation.
Source code in src/mcp/types/methods.py 
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def validate_client_result(
    method: str,
    version: str,
    data: Mapping[str, Any],
    *,
    surface: Mapping[tuple[str, str], type[BaseModel] | UnionType] = CLIENT_RESULTS,
) -> None:
    """Validate a client result against `surface` only.

    Raises:
        ValueError: `version` is not a known protocol version.
        KeyError: `(method, version)` is not in `surface`.
        pydantic.ValidationError: result fails surface validation.
    """
    _check_known_version(version)
    _adapter(surface[(method, version)]).validate_python(data, by_name=False)

parse_client_result 

parse_client_result(
    method: str,
    version: str,
    data: Mapping[str, Any],
    *,
    surface: Mapping[
        tuple[str, str], type[BaseModel] | UnionType
    ] = CLIENT_RESULTS,
    monolith: Mapping[
        str, type[Result] | UnionType
    ] = MONOLITH_RESULTS
) -> Result

Validate a client result against surface, then parse and return its monolith model.

Parameters:

Name Type Description Default
surface Mapping[tuple[str, str], type[BaseModel] | UnionType]

(method, version) to wire-type map; the version-gate lookup and (per-schema-era) shape check run against this. Pass an extended map to admit custom methods.

 CLIENT_RESULTS
monolith Mapping[str, type[Result] | UnionType]

method to version-free model map; the returned instance is parsed from this row. Must cover every method surface admits.

 MONOLITH_RESULTS

Raises:

Type Description
ValueError

version is not a known protocol version.
KeyError

(method, version) is not in surface.
ValidationError

result fails surface or monolith validation.
RuntimeError

surface matched but method has no monolith row.
Source code in src/mcp/types/methods.py 
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def parse_client_result(
    method: str,
    version: str,
    data: Mapping[str, Any],
    *,
    surface: Mapping[tuple[str, str], type[BaseModel] | UnionType] = CLIENT_RESULTS,
    monolith: Mapping[str, type[types.Result] | UnionType] = MONOLITH_RESULTS,
) -> types.Result:
    """Validate a client result against `surface`, then parse and return its `monolith` model.

    Args:
        surface: `(method, version)` to wire-type map; the version-gate lookup
            and (per-schema-era) shape check run against this. Pass an extended
            map to admit custom methods.
        monolith: `method` to version-free model map; the returned instance is
            parsed from this row. Must cover every method `surface` admits.

    Raises:
        ValueError: `version` is not a known protocol version.
        KeyError: `(method, version)` is not in `surface`.
        pydantic.ValidationError: result fails surface or monolith validation.
        RuntimeError: surface matched but `method` has no monolith row.
    """
    validate_client_result(method, version, data, surface=surface)
    result: types.Result = _adapter(_monolith_row(monolith, method)).validate_python(data, by_name=False)
    return result