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当需要调用MCP Server的多个tool时,MCP Client在调用第二个tool时出现反序列化错误(When multiple tools of the MCP Server need to be called, the MCP Client encounters a deserialization error when calling the second tool.)
Bug description
英语不好中文描述了哈
我实现了一个通过百度进行天气查询的MCP Server,实现了两个Tool:String getDistrictId(String district)和String getWeatherForecastDistrictId(String districtId),在使用Spring AI的MCP Client进行查询”济南今天的天气“时,报如下错误,从基本的分析情况看时在调用getWeatherForecastDistrictId这个tool时出现的了错误,初步排查时第一次调用getDistrictId返回的response里text已经是String了,然后调用大模型获取下次需要调用的tool时给出的toolInputArguments应该时一个可以反序列化为Map的String,但实际给出的是'{"districtId": "370100"}',因此再次反序列化出现错误
2025-04-19T15:07:06.172+08:00 DEBUG 4904 --- [mcp] [nio-8089-exec-1] o.s.a.m.tool.DefaultToolCallingManager : Executing tool call: spring_ai_mcp_client_server1_getWeatherForecastDistrictId
2025-04-19T15:07:06.193+08:00 DEBUG 4904 --- [mcp] [nio-8089-exec-1] o.s.web.servlet.DispatcherServlet : Failed to complete request: java.lang.RuntimeException: com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of java.util.HashMap (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('{"districtId": "370100"}')
at [Source: REDACTED (StreamReadFeature.INCLUDE_SOURCE_IN_LOCATION disabled); line: 1, column: 1]
2025-04-19T15:07:06.195+08:00 ERROR 4904 --- [mcp] [nio-8089-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed: java.lang.RuntimeException: com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of java.util.HashMap (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('{"districtId": "370100"}')
at [Source: REDACTED (StreamReadFeature.INCLUDE_SOURCE_IN_LOCATION disabled); line: 1, column: 1]] with root cause
com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of java.util.HashMap (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('{"districtId": "370100"}')
at [Source: REDACTED (StreamReadFeature.INCLUDE_SOURCE_IN_LOCATION disabled); line: 1, column: 1]
at com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:63) ~[jackson-databind-2.17.3.jar:2.17.3]
at com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1754) ~[jackson-databind-2.17.3.jar:2.17.3]
at com.fasterxml.jackson.databind.DeserializationContext.handleMissingInstantiator(DeserializationContext.java:1379) ~[jackson-databind-2.17.3.jar:2.17.3]
at com.fasterxml.jackson.databind.deser.std.StdDeserializer._deserializeFromString(StdDeserializer.java:311) ~[jackson-databind-2.17.3.jar:2.17.3]
at com.fasterxml.jackson.databind.deser.std.MapDeserializer.deserialize(MapDeserializer.java:454) ~[jackson-databind-2.17.3.jar:2.17.3]
at com.fasterxml.jackson.databind.deser.std.MapDeserializer.deserialize(MapDeserializer.java:32) ~[jackson-databind-2.17.3.jar:2.17.3]
at com.fasterxml.jackson.databind.deser.DefaultDeserializationContext.readRootValue(DefaultDeserializationContext.java:342) ~[jackson-databind-2.17.3.jar:2.17.3]
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4905) ~[jackson-databind-2.17.3.jar:2.17.3]
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3848) ~[jackson-databind-2.17.3.jar:2.17.3]
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3831) ~[jackson-databind-2.17.3.jar:2.17.3]
at org.springframework.ai.model.ModelOptionsUtils.jsonToMap(ModelOptionsUtils.java:91) ~[spring-ai-model-1.0.0-M7.jar:1.0.0-M7]
at org.springframework.ai.mcp.SyncMcpToolCallback.call(SyncMcpToolCallback.java:112) ~[spring-ai-mcp-1.0.0-M7.jar:1.0.0-M7]
at org.springframework.ai.mcp.SyncMcpToolCallback.call(SyncMcpToolCallback.java:125) ~[spring-ai-mcp-1.0.0-M7.jar:1.0.0-M7]
at org.springframework.ai.model.tool.DefaultToolCallingManager.executeToolCall(DefaultToolCallingManager.java:227) ~[spring-ai-model-1.0.0-M7.jar:1.0.0-M7]
at org.springframework.ai.model.tool.DefaultToolCallingManager.executeToolCalls(DefaultToolCallingManager.java:139) ~[spring-ai-model-1.0.0-M7.jar:1.0.0-M7]
at org.springframework.ai.openai.OpenAiChatModel.internalCall(OpenAiChatModel.java:242) ~[spring-ai-openai-1.0.0-M7.jar:1.0.0-M7]
at org.springframework.ai.openai.OpenAiChatModel.internalCall(OpenAiChatModel.java:252) ~[spring-ai-openai-1.0.0-M7.jar:1.0.0-M7]
at org.springframework.ai.openai.OpenAiChatModel.call(OpenAiChatModel.java:180) ~[spring-ai-openai-1.0.0-M7.jar:1.0.0-M7]
at org.springframework.ai.chat.client.DefaultChatClient$DefaultChatClientRequestSpec$1.aroundCall(DefaultChatClient.java:680) ~[spring-ai-client-chat-1.0.0-M7.jar:1.0.0-M7]
at org.springframework.ai.chat.client.advisor.DefaultAroundAdvisorChain.lambda$nextAroundCall$1(DefaultAroundAdvisorChain.java:98) ~[spring-ai-client-chat-1.0.0-M7.jar:1.0.0-M7]
at io.micrometer.observation.Observation.observe(Observation.java:565) ~[micrometer-observation-1.13.8.jar:1.13.8]
at org.springframework.ai.chat.client.advisor.DefaultAroundAdvisorChain.nextAroundCall(DefaultAroundAdvisorChain.java:98) ~[spring-ai-client-chat-1.0.0-M7.jar:1.0.0-M7]
at org.springframework.ai.chat.client.DefaultChatClient$DefaultCallResponseSpec.doGetChatResponse(DefaultChatClient.java:493) ~[spring-ai-client-chat-1.0.0-M7.jar:1.0.0-M7]
at org.springframework.ai.chat.client.DefaultChatClient$DefaultCallResponseSpec.lambda$doGetObservableChatResponse$1(DefaultChatClient.java:482) ~[spring-ai-client-chat-1.0.0-M7.jar:1.0.0-M7]
at io.micrometer.observation.Observation.observe(Observation.java:565) ~[micrometer-observation-1.13.8.jar:1.13.8]
at org.springframework.ai.chat.client.DefaultChatClient$DefaultCallResponseSpec.doGetObservableChatResponse(DefaultChatClient.java:482) ~[spring-ai-client-chat-1.0.0-M7.jar:1.0.0-M7]
at org.springframework.ai.chat.client.DefaultChatClient$DefaultCallResponseSpec.doGetChatResponse(DefaultChatClient.java:466) ~[spring-ai-client-chat-1.0.0-M7.jar:1.0.0-M7]
at org.springframework.ai.chat.client.DefaultChatClient$DefaultCallResponseSpec.content(DefaultChatClient.java:516) ~[spring-ai-client-chat-1.0.0-M7.jar:1.0.0-M7]
at com.junxi.demo.ai.mcp.client.ctrl.WeatherWithMPCController.chat(WeatherWithMPCController.java:37) ~[classes/:na]
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:580) ~[na:na]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:255) ~[spring-web-6.1.15.jar:6.1.15]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:188) ~[spring-web-6.1.15.jar:6.1.15]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:118) ~[spring-webmvc-6.1.15.jar:6.1.15]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:926) ~[spring-webmvc-6.1.15.jar:6.1.15]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:831) ~[spring-webmvc-6.1.15.jar:6.1.15]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-6.1.15.jar:6.1.15]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1089) ~[spring-webmvc-6.1.15.jar:6.1.15]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:979) ~[spring-webmvc-6.1.15.jar:6.1.15]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1014) ~[spring-webmvc-6.1.15.jar:6.1.15]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:903) ~[spring-webmvc-6.1.15.jar:6.1.15]
at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:564) ~[tomcat-embed-core-10.1.33.jar:6.0]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:885) ~[spring-webmvc-6.1.15.jar:6.1.15]
at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:658) ~[tomcat-embed-core-10.1.33.jar:6.0]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:195) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51) ~[tomcat-embed-websocket-10.1.33.jar:10.1.33]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-6.1.15.jar:6.1.15]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.1.15.jar:6.1.15]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-6.1.15.jar:6.1.15]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.1.15.jar:6.1.15]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.springframework.web.filter.ServerHttpObservationFilter.doFilterInternal(ServerHttpObservationFilter.java:113) ~[spring-web-6.1.15.jar:6.1.15]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.1.15.jar:6.1.15]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-6.1.15.jar:6.1.15]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.1.15.jar:6.1.15]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:167) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:90) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:483) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:115) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:93) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:344) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:397) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:63) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:905) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1741) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1190) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:63) ~[tomcat-embed-core-10.1.33.jar:10.1.33]
at java.base/java.lang.Thread.run(Thread.java:1583) ~[na:na]
Environment Please provide as many details as possible: Spring AI version, Java version, which vector store you use if any, etc Spring AI version:1.0.0-M7 java version:21.0.2
Steps to reproduce
Steps to reproduce the issue.
MCP Server实现见如上;MCP Client的核心实现如如下:
this.chatClient = chatClientBuilder
.defaultSystem("你是一个专业的智能助手,回答需简洁准确")
.defaultOptions(OpenAiChatOptions.builder()
.model("Qwen/QwQ-32B")
.build())
.defaultTools(tools)
.build();
Expected behavior A clear and concise description of what you expected to happen. 根据实现预期应该是跟调用getDistrictId获取到济南的城市ID,然后调用getWeatherForecastDistrictId根据城市ID获取到济南当地的天气情况,实际在调用getWeatherForecastDistrictId时出现了上述的错误。
Minimal Complete Reproducible example MCP Server的实现如下:
public class BaiDuWeatherService {
// 百度免费天气API基础URL
private static final String BASE_URL = "https://api.map.baidu.com";
private final RestClient restClient;
public BaiDuWeatherService() {
this.restClient = RestClient.builder()
.baseUrl(BASE_URL)
.defaultHeader("Accept", "application/json")
.build();
}
@Tool(description = "根据城市名称获取城市ID")
public String getDistrictId(@ToolParam(description = "城市名称") String district) {
return new BaiDuTools().getDistrictId(district);
}
@Tool(description = "根据城市ID获取天气")
public String getWeatherForecastDistrictId(@ToolParam(description = "城市Id") String districtId) {
String res = restClient.get()
.uri(new BaiDuTools().getSn(districtId))
.retrieve()
.body(String.class);
System.out.println(res);
return res;
}
public static void main(String[] args) {
BaiDuWeatherService service = new BaiDuWeatherService();
// System.out.println(service.getWeatherForecastDistrictId(service.getDistrictId("北京")));
}
}
BaiDuTools实现:
public class BaiDuTools {
private static final String sk = "百度的SK"; //需替换为正式的
private static final String ak = "百度的ak"; //需替换为正式的
private static final Map<String, String> districts = new HashMap<>(4600); //总共3395个区县
static {
String csvFilePath = "F:\\Downloads\\weather_district_id.csv";
String districtHeader = "district";
String districtIdHeader = "district_id";
try (BufferedReader reader = new BufferedReader(new FileReader(csvFilePath));
CSVParser csvParser = new CSVParser(reader, CSVFormat.DEFAULT.withFirstRecordAsHeader())
/*csvParser = new CSVParser(reader, CSVFormat.DEFAULT.builder().setHeader(districtIdHeader, districtHeader).setSkipHeaderRecord(true).build())*/) {
CSVFormat.DEFAULT.builder().setSkipHeaderRecord(true);
for (CSVRecord csvRecord : csvParser) {
String district = csvRecord.get(districtHeader);
String districtId = csvRecord.get(districtIdHeader);
districts.put(district, districtId);
}
// 打印HashMap中的内容(可根据需要删除)
for (Map.Entry<String, String> entry : districts.entrySet()) {
System.out.println("District: " + entry.getKey() + ", District ID: " + entry.getValue());
}
} catch (IOException e) {
e.printStackTrace();
}
}
public String getSn(String districtId) {
Map<String, String> paramsMap = new LinkedHashMap<>();
paramsMap.put("district_id", districtId);
paramsMap.put("data_type", "all");
paramsMap.put("ak", ak);
// 调用下面的toQueryString方法,对LinkedHashMap内所有value作utf8编码,拼接返回结果address=%E7%99%BE%E5%BA%A6%E5%A4%A7%E5%8E%A6&output=json&ak=yourak
String paramsStr = toQueryString(paramsMap);
// 对paramsStr前面拼接上/geocoder/v2/?,后面直接拼接yoursk得到/geocoder/v2/?address=%E7%99%BE%E5%BA%A6%E5%A4%A7%E5%8E%A6&output=json&ak=yourakyoursk
// String wholeStr = "/geocoder/v2/?" + paramsStr + sk;
String wholeStr = "/weather/v1/?" + paramsStr + sk;
// 对上面wholeStr再作utf8编码
String tempStr = URLEncoder.encode(wholeStr, StandardCharsets.UTF_8);
System.out.println("sn is " + MD5(tempStr));
// 调用下面的MD5方法得到最后的sn签名7de5a22212ffaa9e326444c75a58f9a0
return "/weather/v1/?" + paramsStr + "&sn=" + MD5(tempStr);
}
public String getDistrictId(String district) {
return districts.get(district);
}
// 对Map内所有value作utf8编码,拼接返回结果
private String toQueryString(Map<?, ?> data) {
StringBuilder queryString = new StringBuilder();
for (Entry<?, ?> pair : data.entrySet()) {
queryString.append(pair.getKey()).append("=");
queryString.append(URLEncoder.encode((String) pair.getValue(),
StandardCharsets.UTF_8)).append("&");
}
if (!queryString.isEmpty()) {
queryString.deleteCharAt(queryString.length() - 1);
}
return queryString.toString();
}
// 来自stackoverflow的MD5计算方法,调用了MessageDigest库函数,并把byte数组结果转换成16进制
private String MD5(String md5) {
try {
java.security.MessageDigest md = java.security.MessageDigest
.getInstance("MD5");
byte[] array = md.digest(md5.getBytes());
StringBuilder sb = new StringBuilder();
for (int i = 0; i < array.length; ++i) {
sb.append(Integer.toHexString((array[i] & 0xFF) | 0x100), 1, 3);
}
return sb.toString();
} catch (java.security.NoSuchAlgorithmException e) {
}
return null;
}
}