McpSchema should be lenient to unknown properties

[eschnou]

Bug description
Following error on start when adding a mcp server (@shinzolabs/hubspot-mcp)

Unrecognized field "description" (class io.modelcontextprotocol.spec.McpSchema$Implementation), not marked as ignorable (2 known properties: "version", "name"])

Environment
Please provide as many details as possible: Spring MCP version, Java version, which vector store you use if any, etc

Using spring-ai-mcp-client-spring-boot-starter with the following configuration for mcp server:

{
  "mcpServers": {
    "hubspot": {
      "command": "npx",
      "args": [
        "@shinzolabs/hubspot-mcp"
      ],
      "env": {
        "HUBSPOT_ACCESS_TOKEN": "pat-***"
      }
    }
  }
}

Steps to reproduce
Just start the service with that particular mcp server.

Expected behavior
Even if the server report additional fields, it should ignore and not crash. You need to add the @JsonIgnoreProperties annotation to the relevant records or make it global through configuration.

[tzolov]

Hi @eschnou,

the ServerInfo name and version fields are mandatory per the MCP specification, as they are marked required in the MCP schema. I recommend submitting a ticket to @shinzolabs/hubspot-mcp to improve their spec compliance.

That said, Spring AI 1.0.0-SNAPSHOT with latest MCP Java SDK 0.8.1 have relaxed JSON field availability requirements. You can try this by updating your spring-ai dependency to 1.0.0-SNAPSHOT (note that you have to replace the spring-ai-mcp-client-spring-boot-starter artifact name to spring-ai-starter-mcp-client the new spring ai artifact naming schema coming in 1.0.0-M7):

<dependency>
    <groupId>org.springframework.ai</groupId>
    <artifactId>spring-ai-starter-mcp-client</artifactId>
</dependency>

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.ai</groupId>
            <artifactId>spring-ai-bom</artifactId>
            <version>1.0.0-SNAPSHOT</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

<repositories>
  <repository>
    <id>spring-snapshots</id>
    <name>Spring Snapshots</name>
    <url>https://repo.spring.io/snapshot</url>
    <releases>
      <enabled>false</enabled>
    </releases>
  </repository>
</repositories>

Let me know if this helps. There are still chances for NPE as the the underlying implementation (relying on the spec) my assume non-empty ServerInfo instance. Let me know how it goes.

[eschnou]

Thanks @tzolov - I've updated to snapshot and it works like a charm. Sorry about that, I should have checked the development branch before opening the issue. I've now seen GH-37 where it got fixed. 👌

[tzolov]

@eschnou, I'm glad it is resolved. Thank you for the valuable feedback.