046 API Reference 6d3e6efb

Spring AI MCP Server API Reference

Complete API documentation for Spring AI MCP server implementations.

Table of Contents

1. Core Annotations
2. Functional Interfaces
3. Configuration Classes
4. Transport Implementations
5. Security Interfaces
6. Utility Classes
7. Property Bindings
8. Event System

Core Annotations

@Tool

Marks a method as an MCP tool that can be invoked by AI models.

Target: Method Retention: Runtime

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface Tool {
    /**
     * Description of what this tool does.
     * Used by AI models to understand when to invoke the tool.
     */
    String description() default "";

    /**
     * Whether this tool requires confirmation before execution.
     */
    boolean requiresConfirmation() default false;

    /**
     * Maximum execution time in milliseconds.
     */
    long maxExecutionTime() default 30000;

    /**
     * Whether execution time should be monitored.
     */
    boolean monitorExecution() default true;
}

Example:

@Tool(
    description = "Get current weather for a city",
    requiresConfirmation = false,
    maxExecutionTime = 5000
)
public WeatherData getWeather(@ToolParam("City name") String city) {
    // Implementation
}

@ToolParam

Documents a parameter for tool methods.

Target: Parameter Retention: Runtime

@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
public @interface ToolParam {
    /**
     * Description of the parameter purpose.
     */
    String value() default "";

    /**
     * Whether this parameter is required.
     */
    boolean required() default true;

    /**
     * Example value for documentation.
     */
    String example() default "";

    /**
     * Default value if not provided.
     */
    String defaultValue() default "";
}

@PromptTemplate

Marks a method as a prompt template provider.

Target: Method Retention: Runtime

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface PromptTemplate {
    /**
     * Unique name of the prompt template.
     */
    String name() default "";

    /**
     * Description of when to use this template.
     */
    String description() default "";

    /**
     * The template string with placeholders.
     * Use {placeholder} syntax for parameters.
     */
    String template() default "";

    /**
     * Model to use for this prompt.
     */
    String model() default "";

    /**
     * Temperature for model generation.
     */
    double temperature() default 0.7;
}

Example:

@PromptTemplate(
    name = "code-review-java",
    description = "Review Java code for best practices",
    template = """
        Review the following Java code:
        ```java
        {code}
        ```
        Focus on: {focusAreas}
        """,
    temperature = 0.3
)
public Prompt createCodeReviewPrompt(@PromptParam("code") String code) {
    // Return populated prompt
}

@PromptParam

Documents a parameter for prompt template methods.

Target: Parameter Retention: Runtime

@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
public @interface PromptParam {
    /**
     * Name of the parameter in the template.
     */
    String value();

    /**
     * Description of the parameter.
     */
    String description() default "";

    /**
     * Whether this parameter is required.
     */
    boolean required() default true;

    /**
     * Example value.
     */
    String example() default "";
}

@EnableMcpServer

Enables MCP server auto-configuration.

Target: Type Retention: Runtime

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Import(McpServerAutoConfiguration.class)
public @interface EnableMcpServer {
    /**
     * Base packages to scan for tools and prompts.
     */
    String[] basePackages() default {};

    /**
     * Whether to enable automatic tool discovery.
     */
    boolean autoDiscovery() default true;

    /**
     * Configuration class to use.
     */
    Class<?>[] configuration() default {};
}

Functional Interfaces

ToolExecutor

Functional interface for tool execution.

@FunctionalInterface
public interface ToolExecutor {
    /**
     * Execute a tool with the given arguments.
     *
     * @param toolName Name of the tool to execute
     * @param arguments Arguments as a map
     * @return Execution result
     * @throws ToolExecutionException if execution fails
     */
    ToolResult execute(String toolName, Map<String, Object> arguments)
            throws ToolExecutionException;
}

ToolFilter

Filter for tool execution.

@FunctionalInterface
public interface ToolFilter {
    /**
     * Determine if a tool should be allowed to execute.
     *
     * @param tool The tool being requested
     * @param context Execution context
     * @return true if tool should be allowed
     */
    boolean isAllowed(Tool tool, ToolExecutionContext context);
}

Default Implementation:

public class DefaultToolFilter implements ToolFilter {
    @Override
    public boolean isAllowed(Tool tool, ToolExecutionContext context) {
        Authentication auth = SecurityContextHolder.getContext().getAuthentication();

        // Admin tools require admin role
        if (tool.getName().startsWith("admin_")) {
            return auth != null && auth.getAuthorities().stream()
                    .anyMatch(a -> a.getAuthority().equals("ROLE_ADMIN"));
        }

        return true;
    }
}

PromptRenderer

Renders prompt templates with parameters.

@FunctionalInterface
public interface PromptRenderer {
    /**
     * Render a prompt template with parameters.
     *
     * @param template The prompt template
     * @param parameters Parameters to substitute
     * @return Rendered prompt
     */
    Prompt render(PromptTemplate template, Map<String, Object> parameters);
}

Configuration Classes

McpServerAutoConfiguration

Auto-configuration for MCP servers.

@Configuration
@AutoConfigureAfter({WebMvcAutoConfiguration.class})
@ConditionalOnClass({McpServer.class})
@ConditionalOnProperty(name = "spring.ai.mcp.enabled", havingValue = "true", matchIfMissing = true)
public class McpServerAutoConfiguration {

    @Bean
    @ConditionalOnMissingBean
    public McpServerProperties mcpProperties() {
        return new McpServerProperties();
    }

    @Bean
    @ConditionalOnMissingBean
    public McpServer mcpServer(
            McpServerProperties properties,
            ObjectProvider<List<Tool>> tools,
            ObjectProvider<List<PromptTemplate>> prompts
    ) {
        McpServer.Builder builder = McpServer.builder()
                .serverInfo(properties.getServer().getName(), properties.getServer().getVersion())
                .transport(createTransport(properties.getTransport()));

        tools.ifAvailable(toolList -> toolList.forEach(builder::tool));
        prompts.ifAvailable(promptList -> promptList.forEach(builder::prompt));

        return builder.build();
    }

    private Transport createTransport(TransportConfig config) {
        // Create transport based on configuration
        return switch (config.getType()) {
            case STDIO -> new StdioTransport();
            case HTTP -> new HttpTransport(config.getHttp().getPort());
            case SSE -> new SseTransport(config.getHttp().getPort(), config.getHttp().getPath());
        };
    }

    @Bean
    @ConditionalOnMissingBean
    public ToolRegistry toolRegistry(ApplicationContext context) {
        ToolRegistry registry = new ToolRegistry();

        Map<String, Object> toolBeans = context.getBeansWithAnnotation(Component.class);
        toolBeans.values().forEach(bean -> {
            Method[] methods = bean.getClass().getMethods();
            for (Method method : methods) {
                if (method.isAnnotationPresent(Tool.class)) {
                    registry.register(Tool.fromMethod(method, bean));
                }
            }
        });

        return registry;
    }
}

McpServerProperties

Configuration properties for MCP server.

@ConfigurationProperties(prefix = "spring.ai.mcp")
public class McpServerProperties {
    private ServerProperties server = new ServerProperties();
    private TransportProperties transport = new TransportProperties();
    private SecurityProperties security = new SecurityProperties();
    private ToolsProperties tools = new ToolsProperties();
    private PromptsProperties prompts = new PromptsProperties();
    private LoggingProperties logging = new LoggingProperties();
    private MetricsProperties metrics = new MetricsProperties();

    @Data
    public static class ServerProperties {
        private String name = "spring-ai-mcp-server";
        private String version = "1.0.0";
        private String description = "Spring AI MCP Server";
    }

    @Data
    public static class TransportProperties {
        private TransportType type = TransportType.STDIO;
        private HttpProperties http = new HttpProperties();

        @Data
        public static class HttpProperties {
            private int port = 8080;
            private String path = "/mcp";
            private CorsProperties cors = new CorsProperties();

            @Data
            public static class CorsProperties {
                private boolean enabled = true;
                private List<String> allowedOrigins = List.of("*");
                private List<String> allowedMethods = List.of("GET", "POST");
                private List<String> allowedHeaders = List.of("*");
            }
        }
    }

    @Data
    public static class SecurityProperties {
        private boolean enabled = false;
        private AuthorizationProperties authorization = new AuthorizationProperties();
        private AuditProperties audit = new AuditProperties();

        @Data
        public static class AuthorizationProperties {
            private AuthorizationMode mode = AuthorizationMode.ROLE_BASED;
            private boolean defaultDeny = true;
            private List<String> allowedTools = List.of();
            private List<String> adminTools = List.of("admin_*");
        }

        @Data
        public static class AuditProperties {
            private boolean enabled = true;
            private List<String> auditedOperations = List.of("*");
        }

        public enum AuthorizationMode {
            NONE, ROLE_BASED, PERMISSION_BASED, ATTRIBUTE_BASED
        }
    }

    @Data
    public static class ToolsProperties {
        private String packageScan = "com.example.mcp.tools";
        private ValidationProperties validation = new ValidationProperties();
        private CachingProperties caching = new CachingProperties();

        @Data
        public static class ValidationProperties {
            private boolean enabled = true;
            private Duration maxExecutionTime = Duration.ofSeconds(30);
            private int maxArgumentsSize = 1000000; // 1MB
        }

        @Data
        public static class CachingProperties {
            private boolean enabled = true;
            private Duration ttl = Duration.ofMinutes(5);
            private int maxSize = 100;
        }
    }

    @Data
    public static class PromptsProperties {
        private String packageScan = "com.example.mcp.prompts";
        private CachingProperties caching = new CachingProperties();

        @Data
        public static class CachingProperties {
            private boolean enabled = true;
            private Duration ttl = Duration.ofHours(1);
            private int maxSize = 1000;
        }
    }

    // Additional nested properties...
}

Transport Implementations

Transport Interface

public interface Transport {
    /**
     * Start the transport.
     */
    void start() throws IOException;

    /**
     * Stop the transport.
     */
    void stop() throws IOException;

    /**
     * Send a message.
     *
     * @param message The message to send
     */
    void send(Message message) throws IOException;

    /**
     * Receive a message.
     *
     * @return The received message
     */
    Message receive() throws IOException;

    /**
     * Check if transport is connected.
     */
    boolean isConnected();
}

StdioTransport

Standard input/output transport for local process communication.

public class StdioTransport implements Transport {
    private final ObjectMapper objectMapper = new ObjectMapper();
    private final BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
    private final PrintWriter writer = new PrintWriter(System.out, true);
    private volatile boolean running = false;

    @Override
    public void start() throws IOException {
        running = true;
        log.info("STDIO transport started");
    }

    @Override
    public void stop() throws IOException {
        running = false;
        reader.close();
        writer.close();
        log.info("STDIO transport stopped");
    }

    @Override
    public void send(Message message) throws IOException {
        String json = objectMapper.writeValueAsString(message);
        writer.println(json);
        writer.flush();
    }

    @Override
    public Message receive() throws IOException {
        String line = reader.readLine();
        if (line == null) {
            throw new EOFException("End of stream");
        }
        return objectMapper.readValue(line, Message.class);
    }

    @Override
    public boolean isConnected() {
        return running;
    }
}

HttpTransport

HTTP transport for remote communication.

public class HttpTransport implements Transport {
    private final int port;
    private final String path;
    private final HttpServer server;
    private final List<Consumer<Message>> messageHandlers = new CopyOnWriteArrayList<>();
    private volatile boolean running = false;

    public HttpTransport(int port, String path) throws IOException {
        this.port = port;
        this.path = path;
        this.server = HttpServer.create(new InetSocketAddress(port), 0);
    }

    @Override
    public void start() throws IOException {
        server.createContext(path, exchange -> {
            if ("POST".equals(exchange.getRequestMethod())) {
                String requestBody = new String(exchange.getRequestBody().readAllBytes());
                Message message = objectMapper.readValue(requestBody, Message.class);

                messageHandlers.forEach(handler -> handler.accept(message));

                String response = "{\"status\":\"acknowledged\"}";
                exchange.sendResponseHeaders(200, response.getBytes().length);
                exchange.getResponseBody().write(response.getBytes());
            }
            exchange.close();
        });

        server.start();
        running = true;
        log.info("HTTP transport started on port {} path {}", port, path);
    }

    @Override
    public void stop() throws IOException {
        server.stop(0);
        running = false;
        log.info("HTTP transport stopped");
    }

    @Override
    public void send(Message message) throws IOException {
        // HTTP transport is request-response based
        throw new UnsupportedOperationException("Use HTTP client for sending");
    }

    @Override
    public Message receive() throws IOException {
        // HTTP transport receives via POST requests
        throw new UnsupportedOperationException("HTTP transport is async");
    }

    public void addMessageHandler(Consumer<Message> handler) {
        messageHandlers.add(handler);
    }

    @Override
    public boolean isConnected() {
        return running;
    }
}

SseTransport

Server-Sent Events transport for real-time communication.

public class SseTransport implements Transport {
    private final int port;
    private final String path;
    private final List<SseEmitter> emitters = new CopyOnWriteArrayList<>();
    private final HttpServer server;
    private volatile boolean running = false;

    public SseTransport(int port, String path) throws IOException {
        this.port = port;
        this.path = path;
        this.server = HttpServer.create(new InetSocketAddress(port), 0);
    }

    @Override
    public void start() throws IOException {
        // SSE endpoint for receiving messages
        server.createContext(path + "/sse", exchange -> {
            if ("GET".equals(exchange.getRequestMethod())) {
                handleSseConnection(exchange);
            }
        });

        // POST endpoint for sending messages
        server.createContext(path, exchange -> {
            if ("POST".equals(exchange.getRequestMethod())) {
                handleMessage(exchange);
            }
        });

        server.start();
        running = true;
        log.info("SSE transport started on port {} path {}", port, path);
    }

    private void handleSseConnection(HttpExchange exchange) throws IOException {
        Headers headers = exchange.getResponseHeaders();
        headers.add("Content-Type", "text/event-stream");
        headers.add("Cache-Control", "no-cache");
        headers.add("Connection", "keep-alive");

        exchange.sendResponseHeaders(200, 0);

        // Keep connection open
        OutputStream os = exchange.getResponseBody();
        emitters.add(new SseEmitter(os, exchange));
    }

    private void handleMessage(HttpExchange exchange) throws IOException {
        String requestBody = new String(exchange.getRequestBody().readAllBytes());
        Message message = objectMapper.readValue(requestBody, Message.class);

        // Send to all SSE clients
        broadcast(message);

        String response = "{\"status\":\"broadcasted\"}";
        exchange.sendResponseHeaders(200, response.getBytes().length);
        exchange.getResponseBody().write(response.getBytes());
        exchange.close();
    }

    private void broadcast(Message message) {
        String data = "data: " + toJson(message) + "\n\n";
        emitters.removeIf(emitter -> !emitter.send(data));
    }

    @Override
    public void send(Message message) throws IOException {
        broadcast(message);
    }

    @Override
    public Message receive() throws IOException {
        // SSE transport is async, use event-driven approach
        throw new UnsupportedOperationException("SSE transport is async");
    }

    // Additional methods...
}

Security Interfaces

ToolValidator

Validates tool arguments and execution context.

public interface ToolValidator {
    /**
     * Validate tool arguments before execution.
     *
     * @param tool The tool being executed
     * @param arguments The provided arguments
     * @throws ValidationException if validation fails
     */
    void validateArguments(Tool tool, Map<String, Object> arguments)
            throws ValidationException;

    /**
     * Validate execution context.
     *
     * @param tool The tool being executed
     * @param context The execution context
     * @throws ValidationException if validation fails
     */
    void validateContext(Tool tool, ToolExecutionContext context)
            throws ValidationException;
}

Implementation Example:

@Component
public class DefaultToolValidator implements ToolValidator {

    private final McpServerProperties properties;

    @Override
    public void validateArguments(Tool tool, Map<String, Object> arguments)
            throws ValidationException {

        // Check argument size
        int size = arguments.toString().getBytes().length;
        if (size > properties.getTools().getValidation().getMaxArgumentsSize()) {
            throw new ValidationException("Arguments too large: " + size + " bytes");
        }

        // Validate based on tool parameter annotations
        Arrays.stream(tool.getMethod().getParameters())
                .filter(param -> param.isAnnotationPresent(ToolParam.class))
                .forEach(param -> validateParameter(param, arguments));
    }

    private void validateParameter(Parameter param, Map<String, Object> arguments) {
        ToolParam annotation = param.getAnnotation(ToolParam.class);
        String paramName = param.getName();

        if (annotation.required() && !arguments.containsKey(paramName)) {
            throw new ValidationException("Required parameter missing: " + paramName);
        }

        Object value = arguments.get(paramName);
        if (value != null) {
            validateParameterType(param.getType(), value, paramName);
            validateParameterContent(value, paramName);
        }
    }

    private void validateParameterType(Class<?> expectedType, Object value, String paramName) {
        if (!expectedType.isAssignableFrom(value.getClass())) {
            throw new ValidationException(
                    String.format("Parameter %s: expected %s, got %s",
                            paramName, expectedType.getSimpleName(), value.getClass().getSimpleName()));
        }
    }

    private void validateParameterContent(Object value, String paramName) {
        if (value instanceof String str) {
            // Check for injection patterns
            if (str.contains(";") || str.contains("&") || str.contains("|")) {
                throw new ValidationException("Invalid characters in parameter: " + paramName);
            }
        }
    }

    @Override
    public void validateContext(Tool tool, ToolExecutionContext context)
            throws ValidationException {

        // Check authentication if required
        if (tool.requiresAuthentication() && !context.isAuthenticated()) {
            throw new ValidationException("Authentication required for tool: " + tool.getName());
        }

        // Check rate limits
        if (exceedsRateLimit(context.getUser(), tool)) {
            throw new ValidationException("Rate limit exceeded for tool: " + tool.getName());
        }
    }

    private boolean exceedsRateLimit(User user, Tool tool) {
        // Implement rate limiting logic
        return false;
    }
}

SecurityContext

Provides security context for tool execution.

public interface SecurityContext {
    /**
     * Get the current authentication.
     */
    Optional<Authentication> getAuthentication();

    /**
     * Check if current user has permission.
     */
    boolean hasPermission(String permission);

    /**
     * Check if current user has any of the given roles.
     */
    boolean hasAnyRole(String... roles);

    /**
     * Get user details if authenticated.
     */
    Optional<UserDetails> getUserDetails();

    /**
     * Validate MFA token if required.
     */
    boolean validateMfaToken(String token);
}

Utility Classes

ToolRegistry

Manages tool registration and lookup.

@Component
public class ToolRegistry {
    private final Map<String, Tool> tools = new ConcurrentHashMap<>();
    private final List<ToolRegistrationListener> listeners = new CopyOnWriteArrayList<>();

    /**
     * Register a tool.
     */
    public void register(Tool tool) {
        tools.put(tool.getName(), tool);
        notifyListeners(tool, ToolEvent.Type.REGISTERED);
    }

    /**
     * Unregister a tool.
     */
    public void unregister(String toolName) {
        Tool removed = tools.remove(toolName);
        if (removed != null) {
            notifyListeners(removed, ToolEvent.Type.UNREGISTERED);
        }
    }

    /**
     * Get a tool by name.
     */
    public Optional<Tool> getTool(String name) {
        return Optional.ofNullable(tools.get(name));
    }

    /**
     * List all tools.
     */
    public List<Tool> listTools() {
        return List.copyOf(tools.values());
    }

    /**
     * Add registration listener.
     */
    public void addListener(ToolRegistrationListener listener) {
        listeners.add(listener);
    }

    private void notifyListeners(Tool tool, ToolEvent.Type type) {
        ToolEvent event = new ToolEvent(tool, type);
        listeners.forEach(listener -> listener.onToolEvent(event));
    }
}

McpMessage

Represents MCP protocol messages.

public final class McpMessage {
    private final String jsonrpc = "2.0";
    private final String id;
    private final String method;
    private final Map<String, Object> params;
    private final Object result;
    private final McpError error;

    private McpMessage(Builder builder) {
        this.id = builder.id;
        this.method = builder.method;
        this.params = builder.params;
        this.result = builder.result;
        this.error = builder.error;
    }

    public static class Builder {
        private String id;
        private String method;
        private Map<String, Object> params;
        private Object result;
        private McpError error;

        public Builder id(String id) {
            this.id = id;
            return this;
        }

        public Builder method(String method) {
            this.method = method;
            return this;
        }

        public Builder params(Map<String, Object> params) {
            this.params = params;
            return this;
        }

        public Builder result(Object result) {
            this.result = result;
            return this;
        }

        public Builder error(McpError error) {
            this.error = error;
            return this;
        }

        public McpMessage build() {
            return new McpMessage(this);
        }
    }

    // Getters and utility methods...
}

McpError

Represents errors in MCP communication.

public class McpError {
    private final int code;
    private final String message;
    private final Map<String, Object> data;

    // Error codes
    public static final int PARSE_ERROR = -32700;
    public static final int INVALID_REQUEST = -32600;
    public static final int METHOD_NOT_FOUND = -32601;
    public static final int INVALID_PARAMS = -32602;
    public static final int INTERNAL_ERROR = -32603;

    public McpError(int code, String message) {
        this.code = code;
        this.message = message;
        this.data = null;
    }

    public McpError(int code, String message, Map<String, Object> data) {
        this.code = code;
        this.message = message;
        this.data = data;
    }

    // Static factory methods...
}

Property Bindings

spring.ai.mcp.*

Main configuration properties.

Rate Limiting Properties

spring:
  ai:
    mcp:
      rate-limiting:
        enabled: true
        requests-per-minute: 100
        burst-capacity: 150
        limit-by: user  # user, ip, global
        redis:
          enabled: true
          host: localhost
          port: 6379

Threading Properties

spring:
  ai:
    mcp:
      threading:
        executor:
          core-pool-size: 10
          max-pool-size: 50
          queue-capacity: 100
          keep-alive-time: 60s
          thread-name-prefix: mcp-
      timeout:
        default: 30s
        per-tool:
          long-running-tool: 5m
          admin-tool: 1m

Event System

McpEvent

Base class for MCP events.

public abstract class McpEvent extends ApplicationEvent {
    private final Instant timestamp;
    private final String source;

    protected McpEvent(Object source, String eventSource) {
        super(source);
        this.timestamp = Instant.now();
        this.source = eventSource;
    }

    public Instant getTimestamp() {
        return timestamp;
    }

    public String getSource() {
        return source;
    }
}

ToolEvent

Events related to tool lifecycle.

public class ToolEvent extends McpEvent {
    public enum Type {
        REGISTERED,
        UNREGISTERED,
        EXECUTED,
        FAILED,
        TIMEOUT
    }

    private final Type type;
    private final Tool tool;
    private final Map<String, Object> metadata;

    public ToolEvent(Tool tool, Type type) {
        this(tool, type, Map.of());
    }

    public ToolEvent(Tool tool, Type type, Map<String, Object> metadata) {
        super(tool, "tool-registry");
        this.type = type;
        this.tool = tool;
        this.metadata = metadata;
    }

    // Getters...
}

PromptEvent

Events related to prompt operations.

public class PromptEvent extends McpEvent {
    public enum Type {
        RENDERED,
        CACHED,
        FAILED
    }

    private final Type type;
    private final PromptTemplate template;
    private final Map<String, Object> parameters;

    public PromptEvent(PromptTemplate template, Type type, Map<String, Object> parameters) {
        super(template, "prompt-renderer");
        this.type = type;
        this.template = template;
        this.parameters = parameters;
    }

    // Getters...
}

Event Listeners

@Component
public class McpEventListener implements ApplicationListener<McpEvent> {

    private final MetricsService metricsService;
    private final AuditService auditService;

    @Override
    public void onApplicationEvent(McpEvent event) {
        switch (event) {
            case ToolEvent toolEvent -> handleToolEvent(toolEvent);
            case PromptEvent promptEvent -> handlePromptEvent(promptEvent);
            default -> log.debug("Unhandled event: {}", event.getClass());
        }
    }

    private void handleToolEvent(ToolEvent event) {
        metricsService.recordToolEvent(
                event.getTool().getName(),
                event.getType(),
                event.getTimestamp()
        );

        if (event.getType() == ToolEvent.Type.FAILED) {
            auditService.logToolFailure(
                    event.getTool(),
                    event.getMetadata()
            );
        }
    }

    private void handlePromptEvent(PromptEvent event) {
        if (event.getType() == PromptEvent.Type.CACHED) {
            metricsService.incrementPromptCacheHit();
        }
    }
}

Async Execution

AsyncToolExecutor

Asynchronous tool execution support.

public class AsyncToolExecutor {
    private final ExecutorService executor;
    private final ToolExecutor delegate;

    public AsyncToolExecutor(ToolExecutor delegate, ExecutorService executor) {
        this.delegate = delegate;
        this.executor = executor;
    }

    public CompletableFuture<ToolResult> executeAsync(
            String toolName,
            Map<String, Object> arguments) {

        return CompletableFuture.supplyAsync(() -> {
            try {
                return delegate.execute(toolName, arguments);
            } catch (ToolExecutionException e) {
                throw new CompletionException(e);
            }
        }, executor);
    }

    public ToolExecutionFuture executeWithTimeout(
            String toolName,
            Map<String, Object> arguments,
            Duration timeout) {

        CompletableFuture<ToolResult> future = executeAsync(toolName, arguments);

        return new ToolExecutionFuture(future, timeout);
    }
}

public class ToolExecutionFuture {
    private final CompletableFuture<ToolResult> future;
    private final Duration timeout;

    public Optional<ToolResult> getResult() throws TimeoutException {
        try {
            return Optional.ofNullable(
                    future.get(timeout.toMillis(), TimeUnit.MILLISECONDS)
            );
        } catch (InterruptedException | ExecutionException e) {
            return Optional.empty();
        }
    }

    public boolean cancel() {
        return future.cancel(true);
    }

    public boolean isDone() {
        return future.isDone();
    }
}

Health Checks

McpHealthIndicator

Spring Boot actuator health check for MCP server.

@Component
public class McpHealthIndicator implements HealthIndicator {

    private final McpServer mcpServer;
    private final ToolRegistry toolRegistry;

    @Override
    public Health health() {
        Health.Builder builder = new Health.Builder();

        try {
            // Check transport
            Transport transport = mcpServer.getTransport();
            builder.withDetail("transport", transport.getClass().getSimpleName());
            builder.withDetail("connected", transport.isConnected());

            // Check tools
            List<Tool> tools = toolRegistry.listTools();
            builder.withDetail("tools.count", tools.size());

            // Sample tool execution
            testToolExecution(builder, tools);

            builder.status(Status.UP);
        } catch (Exception e) {
            builder.status(Status.DOWN)
                    .withDetail("error", e.getMessage());
        }

        return builder.build();
    }

    private void testToolExecution(Health.Builder builder, List<Tool> tools) {
        if (!tools.isEmpty()) {
            Tool sampleTool = tools.get(0);
            try {
                ToolResult result = sampleTool.execute(Map.of());
                builder.withDetail("sampleTool.status", "success");
            } catch (Exception e) {
                builder.withDetail("sampleTool.status", "failed");
                builder.withDetail("sampleTool.error", e.getMessage());
            }
        }
    }
}

Performance Metrics

McpMetrics

Micrometer-based metrics for MCP server.

@Component
public class McpMetrics {

    private final MeterRegistry meterRegistry;

    private Counter toolExecutionsCounter;
    private Timer toolExecutionTimer;
    private DistributionSummary toolArgumentSize;
    private Counter toolFailuresCounter;
    private Counter promptRenderCounter;

    @PostConstruct
    public void initialize() {
        toolExecutionsCounter = Counter.builder("mcp.tool.executions")
                .description("Number of tool executions")
                .register(meterRegistry);

        toolExecutionTimer = Timer.builder("mcp.tool.execution.time")
                .description("Time taken for tool execution")
                .register(meterRegistry);

        toolArgumentSize = DistributionSummary.builder("mcp.tool.arguments.size")
                .description("Size of tool arguments")
                .register(meterRegistry);

        toolFailuresCounter = Counter.builder("mcp.tool.failures")
                .description("Number of tool failures")
                .register(meterRegistry);

        promptRenderCounter = Counter.builder("mcp.prompt.renders")
                .description("Number of prompt renders")
                .register(meterRegistry);
    }

    public void recordToolExecution(String toolName, long durationMs, boolean success) {
        toolExecutionsCounter.increment();
        toolExecutionTimer.record(durationMs, TimeUnit.MILLISECONDS);

        if (!success) {
            toolFailuresCounter.increment();
        }

        Tags tags = Tags.of("tool", toolName, "success", String.valueOf(success));
        meterRegistry.counter("mcp.tool.executions.byTool", tags).increment();
    }

    public void recordPromptRender(String templateName) {
        promptRenderCounter.increment();

        Tags tags = Tags.of("template", templateName);
        meterRegistry.counter("mcp.prompt.renders.byTemplate", tags).increment();
    }

    public void recordArgumentSize(int size) {
        toolArgumentSize.record(size);
    }
}