Invalid params: "id" must be an integer or null if present., data=null]

[ericdallo]

Bug description
Initial issue

When using laravel boost MCP I face

Client failed to initialize by explicit API call

JSONRPCError[code=-32602, message=Invalid params: "id" must be an integer or null if present., data=null]

Environment
version 0.11.3

Steps to reproduce

ServerParameters params = ServerParameters.builder("php")
    .args("artisan", "boost:mcp")
    .build();
McpTransport transport = new StdioClientTransport(params);

McpAsyncClient client = McpClient.async(transport)
    .requestTimeout(Duration.ofSeconds(10))
    .capabilities(ClientCapabilities.builder()
        .roots(true) 
        .build())
    .build();

client.initialize.block(); // throws

Expected behavior
Initialize with no issue server.

Same server works with other clients: Cursor, gptel etc.

[tzolov]

Hi @ericdallo this error seems generated by the laravel server.

Invalid params: "id" must be an integer or null if present.

Can you clarify, please, which Id is the laravel complaining about?

The JSONRPC 2.0 Request specification defines the id attribute like:

An identifier established by the Client that MUST contain a String, Number, or NULL value if included. If it is not included it is assumed to be a notification. The value SHOULD normally not be Null [1] and Numbers SHOULD NOT contain fractional parts

[ericdallo]

@tzolov thanks for the reply, that's the issue, the logs only mention that :/

[ericdallo]

I just wondering how this MCP server works for other clients but not with mcp java sdk

[gjm]

@tzolov @ericdallo If I may contribute, the Laravel Boost MCP server includes an inspector that can be used to get in depth information on the MCP server, including request/response tracing.

It can be accessed via php artisan mcp:inspector laravel-boost.

Maybe this tool will provider further information.

[ericdallo]

After manually calling the server it seems the problem is that the MCP server doesn't support the id as a string but as a integer, @tzolov i know the server should fix that on their side, but is there any workaround on mcp java sdk that could send the initialize as integer instead?

[gjm]

Reported this issue to Laravel Boost (#250).