AL MCP: al_symbolrelations always fails, SymbolRelationsService is not registered in the standalone server #8371

1. Describe the bug

al_symbolrelations is advertised by the standalone AL MCP server (altool launchmcpserver) in tools/list, but every call to it fails. The client only receives the generic An error occurred invoking 'al_symbolrelations'.

The server's stderr shows the cause: the service behind the tool is not registered with the dependency injection container.

fail: ModelContextProtocol.Server.McpServer[1433779783]
      "al_symbolrelations" threw an unhandled exception.
      System.InvalidOperationException: No service for type 'Microsoft.Dynamics.Nav.CodeAnalysis.Workspaces.LanguageModelTools.SymbolRelations.SymbolRelationsService' has been registered.
         at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
         at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider)
         at Microsoft.Dynamics.BusinessCentral.ALMcp.McpServerFactory.<>c.<RegisterSharedServices>b__6_4(IServiceProvider sp) in X:\source\Prod\almcp\Services\McpServerFactory.cs:line 317
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitRootCache(ServiceCallSite callSite, RuntimeResolverContext context)
         ...
         at Microsoft.Extensions.DependencyInjection.McpServerBuilderExtensions.CreateTarget(IServiceProvider services, Type type)
         at ModelContextProtocol.Server.AIFunctionMcpServerTool.InvokeAsync(RequestContext`1 request, CancellationToken cancellationToken)

The failure does not depend on the project or the arguments. I get the same exception:

• with no project loaded, and with projects loaded and their symbols already indexed
• with symbolName + symbolKind (the example in the tool's own description), with symbolId from an al_symbolsearch result, and with empty arguments
• from an MCP client, and from raw JSON-RPC over stdio with no client involved

Other tools on the same server instance answer normally (al_symbolsearch, al_compile, al_inspectpage, al_getnextobjectid), so this looks specific to this tool's registration.

2. To Reproduce

No AL code is needed.

1. Start the server with no project: altool launchmcpserver --transport stdio
2. Send these lines on stdin:

{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-03-26","capabilities":{},"clientInfo":{"name":"repro","version":"1"}}}
{"jsonrpc":"2.0","method":"notifications/initialized"}
{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"al_symbolrelations","arguments":{"parameters":{"symbolName":"Customer","symbolKind":"Table"}}}}

3. Read the response to id 2 on stdout and the exception on stderr.

3. Expected behavior

The tool returns the relations of the symbol. With no project loaded, it returns an actionable message, as al_symbolsearch does: No projects are loaded in the workspace. Use the al_addproject tool to add a project, then retry.

4. Actual behavior

{"result":{"content":[{"type":"text","text":"An error occurred invoking 'al_symbolrelations'."}],"isError":true},"id":2,"jsonrpc":"2.0"}

The exception above is written to stderr only. Nothing about it reaches the file set with --logfile, even at --loglevel Debug.

5. Versions:

• AL Language: 30.0.2863738, the latest pre-release on the Marketplace (altool --version: 30.0.43.45776+9c432ef3dff6a3c4df683465da5f5c539f6a8bf1). Not tested on the release channel (18.1.2842859).
• Visual Studio Code: not involved (standalone altool); 1.144.0 installed
• Business Central: not involved (the call fails before any server connection)
• List of Visual Studio Code extensions that you have installed: not applicable, reproduced outside Visual Studio Code
• Operating System:
  • Windows
  • Linux
  • MacOS

Final Checklist

• Search the issue repository to ensure you are reporting a new issue

• Reproduce the issue after disabling all extensions except the AL Language extension (reproduced outside Visual Studio Code)

• Simplify your code around the issue to better isolate the problem (no code needed)