MCP Registry Client

(Updated: )
AI

https://blog.modelcontextprotocol.io/posts/2025-09-08-mcp-registry-preview/

MCP Registry client

LangChain4j also offers a separate client implementation that can talk to
MCP registries. Right now, only
read-only operations are implemented (you can search for MCP servers, but managing and adding servers
is not supported - please use the
official tools for that).

WARNING: Discovering MCP servers and using them (especially running locally) may present serious security risks. Before
running any MCP server that you locate in a public registry, make sure you can trust it.

The registry client
lives in the dev.langchain4j.mcp.registryclient package and can be initialized like this:

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McpRegistryClient client = DefaultMcpRegistryClient.builder()
        .baseUrl("URL-OF-THE-REGISTRY")
        .build();

If no base URL is provided, the official registry will be used as the default (https://registry.modelcontextprotocol.io).
Then, to search for MCP servers, use the registry.listServers(McpServerListRequest) method. A McpServerListRequest
object can be built using the McpServerListRequest.Builder class. The Java API in LangChain4j
closely mirrors the REST API of MCP registries as described in the official
MCP Registry Reference.