McpClient

This docs was updated at: 2026-02-23

com.paragon.mcp.McpClient  ·  Class

Implements AutoCloseable

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Abstract base class for MCP client implementations.

This class handles the MCP protocol lifecycle and provides common functionality for both Stdio and HTTP transports.

Lifecycle

• .connect() - Establishes connection and performs initialization handshake
• .listTools() / Map) - Perform operations
• .close() - Closes connection and cleans up resources

See Also

• StdioMcpClient
• StreamableHttpMcpClient

Methods

McpClient

protected McpClient(@NonNull ObjectMapper objectMapper)

Creates a new MCP client.

Parameters

Name	Description
objectMapper	the object mapper for JSON serialization

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doConnect

protected abstract void doConnect() throws McpException

Establishes the underlying transport connection.

Throws

Type	Condition
McpException	if connection fails

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sendRequest

protected abstract void sendRequest(@NonNull JsonRpcRequest request) throws McpException

Sends a JSON-RPC request over the transport.

Parameters

Name	Description
request	the request to send

Throws

Type	Condition
McpException	if sending fails

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readResponse

protected abstract @NonNull JsonRpcResponse readResponse() throws McpException

Reads a JSON-RPC response from the transport.

Returns

the response

Throws

Type	Condition
McpException	if reading fails

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doClose

protected abstract void doClose() throws McpException

Closes the underlying transport connection.

Throws

Type	Condition
McpException	if closing fails

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connect

public void connect() throws McpException

Connects to the MCP server and performs initialization.

This method establishes the transport connection, sends the initialize request, and sends the initialized notification.

Throws

Type	Condition
McpException	if connection or initialization fails

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listTools

public @NonNull List<McpToolDefinition> listTools() throws McpException

Lists all tools available on the MCP server.

Returns

the list of tool definitions

Throws

Type	Condition
McpException	if listing fails or client not initialized

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callTool

public @NonNull McpToolResult callTool(
      @NonNull String name, @Nullable Map<String, Object> arguments) throws McpException

Calls a tool on the MCP server.

Parameters

Name	Description
name	the tool name
arguments	the tool arguments

Returns

the tool result

Throws

Type	Condition
McpException	if the call fails or client not initialized

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asTools

public @NonNull List<McpRemoteTool> asTools() throws McpException

Returns all MCP tools as McpRemoteTool instances that can be used with agents.

Returns

list of MCP remote tools

Throws

Type	Condition
McpException	if listing fails

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asTools

public @NonNull List<McpRemoteTool> asTools(@Nullable Set<String> allowedToolNames)
      throws McpException

Returns filtered MCP tools as McpRemoteTool instances.

Parameters

Name	Description
allowedToolNames	optional set of tool names to include (null for all)

Returns

list of MCP remote tools

Throws

Type	Condition
McpException	if listing fails

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toJson

protected @NonNull String toJson(@NonNull Object obj) throws McpException

Serializes an object to JSON string.

Parameters

Name	Description
obj	the object to serialize

Returns

the JSON string

Throws

Type	Condition
McpException	if serialization fails

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parseResponse

protected @NonNull JsonRpcResponse parseResponse(@NonNull String json) throws McpException

Deserializes a JSON string to JsonRpcResponse.

Parameters

Name	Description
json	the JSON string

Returns

the parsed response

Throws

Type	Condition
McpException	if parsing fails