io.modelcontextprotocol.client

Class McpClient.AsyncSpec

java.lang.Object

io.modelcontextprotocol.client.McpClient.AsyncSpec

Enclosing interface:

McpClient

public static class McpClient.AsyncSpec
extends Object

Asynchronous client specification. This class follows the builder pattern to provide a fluent API for setting up clients with custom configurations.

The builder supports configuration of:

• Transport layer for client-server communication
• Request timeouts for operation boundaries
• Client capabilities for feature negotiation
• Client implementation details for version tracking
• Root URIs for resource access
• Change notification handlers for tools, resources, and prompts
• Custom message sampling logic

Method Summary

Modifier and Type	Method and Description
McpAsyncClient	build() Create an instance of McpAsyncClient with the provided configurations or sensible defaults.
McpClient.AsyncSpec	capabilities(McpSchema.ClientCapabilities capabilities) Sets the client capabilities that will be advertised to the server during connection initialization.
McpClient.AsyncSpec	clientInfo(McpSchema.Implementation clientInfo) Sets the client implementation information that will be shared with the server during connection initialization.
McpClient.AsyncSpec	initializationTimeout(Duration initializationTimeout)
McpClient.AsyncSpec	loggingConsumer(Function<McpSchema.LoggingMessageNotification,reactor.core.publisher.Mono<Void>> loggingConsumer) Adds a consumer to be notified when logging messages are received from the server.
McpClient.AsyncSpec	loggingConsumers(List<Function<McpSchema.LoggingMessageNotification,reactor.core.publisher.Mono<Void>>> loggingConsumers) Adds multiple consumers to be notified when logging messages are received from the server.
McpClient.AsyncSpec	promptsChangeConsumer(Function<List<McpSchema.Prompt>,reactor.core.publisher.Mono<Void>> promptsChangeConsumer) Adds a consumer to be notified when the available prompts change.
McpClient.AsyncSpec	requestTimeout(Duration requestTimeout) Sets the duration to wait for server responses before timing out requests.
McpClient.AsyncSpec	resourcesChangeConsumer(Function<List<McpSchema.Resource>,reactor.core.publisher.Mono<Void>> resourcesChangeConsumer) Adds a consumer to be notified when the available resources change.
McpClient.AsyncSpec	roots(List<McpSchema.Root> roots) Sets the root URIs that this client can access.
McpClient.AsyncSpec	roots(McpSchema.Root... roots) Sets the root URIs that this client can access, using a varargs parameter for convenience.
McpClient.AsyncSpec	sampling(Function<McpSchema.CreateMessageRequest,reactor.core.publisher.Mono<McpSchema.CreateMessageResult>> samplingHandler) Sets a custom sampling handler for processing message creation requests.
McpClient.AsyncSpec	toolsChangeConsumer(Function<List<McpSchema.Tool>,reactor.core.publisher.Mono<Void>> toolsChangeConsumer) Adds a consumer to be notified when the available tools change.
McpClient.AsyncSpec	withConnectOnInit(boolean connectOnInit) Sets whether to connect to the server during the initialization phase (open an SSE stream).

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

requestTimeout

public McpClient.AsyncSpec requestTimeout(Duration requestTimeout)

Sets the duration to wait for server responses before timing out requests. This timeout applies to all requests made through the client, including tool calls, resource access, and prompt operations.

Parameters:

requestTimeout - The duration to wait before timing out requests. Must not be null.

Returns:

This builder instance for method chaining

Throws:

IllegalArgumentException - if requestTimeout is null

withConnectOnInit

public McpClient.AsyncSpec withConnectOnInit(boolean connectOnInit)

Sets whether to connect to the server during the initialization phase (open an SSE stream).

Parameters:

connectOnInit - true to open an SSE stream during the initialization

Returns:

This builder instance for method chaining

initializationTimeout

public McpClient.AsyncSpec initializationTimeout(Duration initializationTimeout)

Parameters:

initializationTimeout - The duration to wait for the initializaiton lifecycle step to complete.

Returns:

This builder instance for method chaining

Throws:

IllegalArgumentException - if initializationTimeout is null

capabilities

public McpClient.AsyncSpec capabilities(McpSchema.ClientCapabilities capabilities)

Sets the client capabilities that will be advertised to the server during connection initialization. Capabilities define what features the client supports, such as tool execution, resource access, and prompt handling.

Parameters:

capabilities - The client capabilities configuration. Must not be null.

Returns:

This builder instance for method chaining

Throws:

IllegalArgumentException - if capabilities is null

clientInfo

public McpClient.AsyncSpec clientInfo(McpSchema.Implementation clientInfo)

Sets the client implementation information that will be shared with the server during connection initialization. This helps with version compatibility and debugging.

Parameters:

clientInfo - The client implementation details including name and version. Must not be null.

Returns:

This builder instance for method chaining

Throws:

IllegalArgumentException - if clientInfo is null

roots

public McpClient.AsyncSpec roots(List<McpSchema.Root> roots)

Sets the root URIs that this client can access. Roots define the base URIs for resources that the client can request from the server. For example, a root might be "file://workspace" for accessing workspace files.

Parameters:

roots - A list of root definitions. Must not be null.

Returns:

This builder instance for method chaining

Throws:

IllegalArgumentException - if roots is null

roots

public McpClient.AsyncSpec roots(McpSchema.Root... roots)

Sets the root URIs that this client can access, using a varargs parameter for convenience. This is an alternative to roots(List).

Parameters:

roots - An array of root definitions. Must not be null.

Returns:

This builder instance for method chaining

Throws:

IllegalArgumentException - if roots is null

See Also:

roots(List)

sampling

public McpClient.AsyncSpec sampling(Function<McpSchema.CreateMessageRequest,reactor.core.publisher.Mono<McpSchema.CreateMessageResult>> samplingHandler)

Sets a custom sampling handler for processing message creation requests. The sampling handler can modify or validate messages before they are sent to the server, enabling custom processing logic.

Parameters:

samplingHandler - A function that processes message requests and returns results. Must not be null.

Returns:

This builder instance for method chaining

Throws:

IllegalArgumentException - if samplingHandler is null

toolsChangeConsumer

public McpClient.AsyncSpec toolsChangeConsumer(Function<List<McpSchema.Tool>,reactor.core.publisher.Mono<Void>> toolsChangeConsumer)

Adds a consumer to be notified when the available tools change. This allows the client to react to changes in the server's tool capabilities, such as tools being added or removed.

Parameters:

toolsChangeConsumer - A consumer that receives the updated list of available tools. Must not be null.

Returns:

This builder instance for method chaining

Throws:

IllegalArgumentException - if toolsChangeConsumer is null

resourcesChangeConsumer

public McpClient.AsyncSpec resourcesChangeConsumer(Function<List<McpSchema.Resource>,reactor.core.publisher.Mono<Void>> resourcesChangeConsumer)

Adds a consumer to be notified when the available resources change. This allows the client to react to changes in the server's resource availability, such as files being added or removed.

Parameters:

resourcesChangeConsumer - A consumer that receives the updated list of available resources. Must not be null.

Returns:

This builder instance for method chaining

Throws:

IllegalArgumentException - if resourcesChangeConsumer is null

promptsChangeConsumer

public McpClient.AsyncSpec promptsChangeConsumer(Function<List<McpSchema.Prompt>,reactor.core.publisher.Mono<Void>> promptsChangeConsumer)

Adds a consumer to be notified when the available prompts change. This allows the client to react to changes in the server's prompt templates, such as new templates being added or existing ones being modified.

Parameters:

promptsChangeConsumer - A consumer that receives the updated list of available prompts. Must not be null.

Returns:

This builder instance for method chaining

Throws:

IllegalArgumentException - if promptsChangeConsumer is null

loggingConsumer

public McpClient.AsyncSpec loggingConsumer(Function<McpSchema.LoggingMessageNotification,reactor.core.publisher.Mono<Void>> loggingConsumer)

Adds a consumer to be notified when logging messages are received from the server. This allows the client to react to log messages, such as warnings or errors, that are sent by the server.

Parameters:

loggingConsumer - A consumer that receives logging messages. Must not be null.

Returns:

This builder instance for method chaining

loggingConsumers

public McpClient.AsyncSpec loggingConsumers(List<Function<McpSchema.LoggingMessageNotification,reactor.core.publisher.Mono<Void>>> loggingConsumers)

Adds multiple consumers to be notified when logging messages are received from the server. This allows the client to react to log messages, such as warnings or errors, that are sent by the server.

Parameters:

loggingConsumers - A list of consumers that receive logging messages. Must not be null.

Returns:

This builder instance for method chaining

build

public McpAsyncClient build()

Create an instance of McpAsyncClient with the provided configurations or sensible defaults.

Returns:

a new instance of McpAsyncClient.