Class MultiServerMCPClient

Client for connecting to multiple MCP servers and loading LangChain-compatible tools.

Constructors

constructor

Accessors

config

Methods

close getClient getTools initializeConnections

Constructors

constructor

  • new MultiServerMCPClient(config): MultiServerMCPClient

  • Create a new MultiServerMCPClient.

    Parameters

    • config: Record<string, {
          args: string[];
          command: string;
          cwd?: string;
          encoding?: string;
          env?: Record<string, string>;
          restart?: {
              delayMs?: number;
              enabled?: boolean;
              maxAttempts?: number;
          };
          stderr?:
              | "overlapped"
              | "pipe"
              | "ignore"
              | "inherit";
          transport?: "stdio";
          type?: "stdio";
      } | {
          automaticSSEFallback?: boolean;
          headers?: Record<string, string>;
          reconnect?: {
              delayMs?: number;
              enabled?: boolean;
              maxAttempts?: number;
          };
          transport?: "http" | "sse";
          type?: "http" | "sse";
          url: string;
          useNodeEventSource?: boolean;
      }> | {
          additionalToolNamePrefix?: string;
          mcpServers: Record<string, {
              args: string[];
              command: string;
              cwd?: string;
              encoding?: string;
              env?: Record<string, string>;
              restart?: {
                  delayMs?: number;
                  enabled?: boolean;
                  maxAttempts?: number;
              };
              stderr?:
                  | "overlapped"
                  | "pipe"
                  | "ignore"
                  | "inherit";
              transport?: "stdio";
              type?: "stdio";
          } | {
              automaticSSEFallback?: boolean;
              headers?: Record<string, string>;
              reconnect?: {
                  delayMs?: number;
                  enabled?: boolean;
                  maxAttempts?: number;
              };
              transport?: "http" | "sse";
              type?: "http" | "sse";
              url: string;
              useNodeEventSource?: boolean;
          }>;
          prefixToolNameWithServerName?: boolean;
          throwOnLoadError?: boolean;
      }

    Returns MultiServerMCPClient

Accessors

config

  • get config(): {
        additionalToolNamePrefix?: string;
        mcpServers: Record<string, {
            args: string[];
            command: string;
            cwd?: string;
            encoding?: string;
            env?: Record<string, string>;
            restart?: {
                delayMs?: number;
                enabled?: boolean;
                maxAttempts?: number;
            };
            stderr?:
                | "overlapped"
                | "pipe"
                | "ignore"
                | "inherit";
            transport?: "stdio";
            type?: "stdio";
        } | {
            automaticSSEFallback?: boolean;
            headers?: Record<string, string>;
            reconnect?: {
                delayMs?: number;
                enabled?: boolean;
                maxAttempts?: number;
            };
            transport?: "http" | "sse";
            type?: "http" | "sse";
            url: string;
            useNodeEventSource?: boolean;
        }>;
        prefixToolNameWithServerName?: boolean;
        throwOnLoadError?: boolean;
    }

  • Returns clone of server config for inspection purposes.

    Client does not support config modifications.

    Returns {
        additionalToolNamePrefix?: string;
        mcpServers: Record<string, {
            args: string[];
            command: string;
            cwd?: string;
            encoding?: string;
            env?: Record<string, string>;
            restart?: {
                delayMs?: number;
                enabled?: boolean;
                maxAttempts?: number;
            };
            stderr?:
                | "overlapped"
                | "pipe"
                | "ignore"
                | "inherit";
            transport?: "stdio";
            type?: "stdio";
        } | {
            automaticSSEFallback?: boolean;
            headers?: Record<string, string>;
            reconnect?: {
                delayMs?: number;
                enabled?: boolean;
                maxAttempts?: number;
            };
            transport?: "http" | "sse";
            type?: "http" | "sse";
            url: string;
            useNodeEventSource?: boolean;
        }>;
        prefixToolNameWithServerName?: boolean;
        throwOnLoadError?: boolean;
    }

    • OptionaladditionalToolNamePrefix?: string

      An additional prefix to add to the tool name Prefixes are separated by double underscores (example: mcp__add).

      Default

      "mcp"
    • mcpServers: Record<string, {
          args: string[];
          command: string;
          cwd?: string;
          encoding?: string;
          env?: Record<string, string>;
          restart?: {
              delayMs?: number;
              enabled?: boolean;
              maxAttempts?: number;
          };
          stderr?:
              | "overlapped"
              | "pipe"
              | "ignore"
              | "inherit";
          transport?: "stdio";
          type?: "stdio";
      } | {
          automaticSSEFallback?: boolean;
          headers?: Record<string, string>;
          reconnect?: {
              delayMs?: number;
              enabled?: boolean;
              maxAttempts?: number;
          };
          transport?: "http" | "sse";
          type?: "http" | "sse";
          url: string;
          useNodeEventSource?: boolean;
      }>

      A map of server names to their configuration

    • OptionalprefixToolNameWithServerName?: boolean

      Whether to prefix tool names with the server name. Prefixes are separated by double underscores (example: calculator_server_1__add).

      Default

      true
    • OptionalthrowOnLoadError?: boolean

      Whether to throw an error if a tool fails to load

      Default

      true

Methods

close

getClient

  • getClient(serverName): Promise<undefined | Client<{
        method: string;
        params?: {};
    }, {
        method: string;
        params?: {};
    }, {}>>

  • Get a the MCP client for a specific server. Useful for fetching prompts or resources from that server.

    Parameters

    • serverName: string

      The name of the server

    Returns Promise<undefined | Client<{
        method: string;
        params?: {};
    }, {
        method: string;
        params?: {};
    }, {}>>

    The client for the server, or undefined if the server is not connected

getTools

  • getTools(...servers): Promise<StructuredToolInterface<ToolInputSchemaBase, any, any>[]>

  • Get tools from specified servers as a flattened array.

    Parameters

    • Rest...servers: string[]

      Optional array of server names to filter tools by. If not provided, returns tools from all servers.

    Returns Promise<StructuredToolInterface<ToolInputSchemaBase, any, any>[]>

    A flattened array of tools from the specified servers (or all servers)

initializeConnections

  • initializeConnections(): Promise<Record<string, StructuredToolInterface<ToolInputSchemaBase, any, any>[]>>

  • Proactively initialize connections to all servers. This will be called automatically when methods requiring an active connection (like getTools or getClient) are called, but you can call it directly to ensure all connections are established before using the tools.

    Returns Promise<Record<string, StructuredToolInterface<ToolInputSchemaBase, any, any>[]>>

    A map of server names to arrays of tools

    Throws

    If initialization fails

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