mcp

ClientResult = (
    EmptyResult
    | CreateMessageResult
    | CreateMessageResultWithTools
    | ListRootsResult
    | ElicitResult
)

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class InputRequiredRoundsExceededError(RuntimeError):
    """The server kept returning `InputRequiredResult` past the configured `max_rounds`."""

    def __init__(self, max_rounds: int) -> None:
        super().__init__(
            f"Server returned InputRequiredResult for more than {max_rounds} rounds; "
            "raise input_required_max_rounds on the Client, or use "
            "client.session.<method>(..., allow_input_required=True) to drive the loop manually."
        )
        self.max_rounds = max_rounds

Classes

• CallToolRequest — Used by the client to invoke a tool provided by the server.
• Client — A high-level MCP client for connecting to MCP servers.
• ClientCapabilities — Capabilities a client may support.
• ClientSession — Client half of an MCP connection, running on a Dispatcher.
• ClientSessionGroup — Client for managing connections to multiple MCP servers.
• CompleteRequest — A request from the client to the server, to ask for completion options.
• CreateMessageRequest — A request from the server to sample an LLM via the client.
• CreateMessageResult — The client's response to a sampling/createMessage request from the server.
• CreateMessageResultWithTools — The client's response to a sampling/createMessage request when tools were provided.
• ErrorData — Error information for JSON-RPC error responses.
• GetPromptRequest — Used by the client to get a prompt provided by the server.
• GetPromptResult — The server's response to a prompts/get request from the client.
• Implementation — Describes the name and version of an MCP implementation (clientInfo / serverInfo).
• InitializedNotification — This notification is sent from the client to the server after initialization has finished.
• InitializeRequest — This request is sent from the client to the server when it first connects, asking it to begin initialization.
• InitializeResult — After receiving an initialize request from the client, the server sends this response.
• InputRequiredRoundsExceededError — The server kept returning InputRequiredResult past the configured max_rounds.
• InvalidUriTemplate — Raised when a URI template string is malformed or unsupported.
• JSONRPCError — A response to a request that indicates an error occurred.
• JSONRPCRequest — A JSON-RPC request that expects a response.
• JSONRPCResponse — A successful (non-error) response to a request.
• ListPromptsRequest — Sent from the client to request a list of prompts and prompt templates the server has.
• ListPromptsResult — The server's response to a prompts/list request from the client.
• ListResourcesRequest — Sent from the client to request a list of resources the server has.
• ListResourcesResult — The server's response to a resources/list request from the client.
• ListToolsResult — The server's response to a tools/list request from the client.
• LoggingMessageNotification — Notification of a log message passed from server to client.
• MCPDeprecationWarning — A custom deprecation warning for the MCP SDK.
• MCPError — Exception type raised when an error arrives over an MCP connection.
• Notification — Base class for JSON-RPC notifications.
• PingRequest — A ping, issued by either the server or the client, to check that the other party is still alive. The receiver must promptly respond, or else may be disconnected.
• ProgressNotification — An out-of-band notification used to inform the receiver of a progress update for a long-running request.
• PromptsCapability — Capability for prompts operations.
• ReadResourceRequest — Sent from the client to the server, to read a specific resource URI.
• ReadResourceResult — The server's response to a resources/read request from the client.
• Resource — A known resource that the server is capable of reading.
• ResourcesCapability — Capability for resources operations.
• ResourceUpdatedNotification — A notification from the server to the client, informing it that a resource has changed and may need to be read again.
• RootsCapability — Capability for root operations.
• SamplingCapability — Sampling capability structure. Deprecated in 2026-07-28 (SEP-2577); shape unchanged.
• SamplingContextCapability — Capability for context inclusion during sampling.
• SamplingMessage — Describes a message issued to or received from an LLM API.
• SamplingToolsCapability — Capability indicating support for tool calling during sampling.
• ServerCapabilities — Capabilities that a server may support. Not a closed set.
• ServerSession — Per-request proxy for server-to-client requests and notifications.
• SetLevelRequest — A request from the client to the server, to enable or adjust logging.
• StdioServerParameters
• SubscribeRequest — Sent from the client to request resources/updated notifications from the server whenever a particular resource changes.
• Tool — Definition for a tool the client can call.
• ToolChoice — Controls tool selection behavior for sampling requests (2025-11-25+).
• ToolResultContent — The result of a tool use, provided by the user back to the assistant (2025-11-25+).
• ToolsCapability — Capability for tools operations.
• ToolUseContent — An assistant's request to invoke a tool during sampling (2025-11-25+).
• UnsubscribeRequest — Sent from the client to request cancellation of resources/updated notifications from the server. This should follow a previous resources/subscribe request.
• UriTemplate — A parsed RFC 6570 URI template.
• UrlElicitationRequiredError — Specialized error for when a tool requires URL mode elicitation(s) before proceeding.

Functions

• stdio_client — Spawns an MCP server subprocess and connects to it over stdin/stdout.
• stdio_server — Server transport for stdio: this communicates with an MCP client by reading from the current process' stdin and writing to stdout.

Attributes

• ClientNotification — Notifications sent from the client to the server.
• ClientRequest — Union of client-to-server request payloads across all supported protocol versions.
• ClientResult
• IncludeContext — Scope of MCP-server context a sampling request asks the client to attach.
• LoggingLevel — The severity of a log message.
• SamplingContent — Basic content types for sampling responses (without tool use).
• SamplingMessageContentBlock — Content block types allowed in sampling messages.
• SamplingRole — The sender or recipient of messages and data in a conversation.
• ServerNotification — Union of server-to-client notification payloads across all supported protocol versions.
• ServerRequest — Union of standalone JSON-RPC requests a server can send to a client.
• ServerResult — Union of every result payload a server can return for a client request.
• StopReason — The reason why sampling stopped, if known.