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Workspace MCP Language Tools

Use this guide when you want AXSG language-service operations over MCP from the standalone workspace host.

This guide is about:

  • axsg-mcp
  • workspace-shaped queries
  • language-service operations that are useful outside an editor

It is not about the live runtime host inside a running Avalonia process.

Use this guide when

  • you need preview project resolution outside VS Code
  • you want metadata-as-source text from an MCP client
  • you need inline C# projections for a custom editor or analysis client
  • you want cross-language references or declarations between C# and XAML
  • you need rename planning or rename propagation over MCP

Start the host

Install:

dotnet tool install --global XamlToCSharpGenerator.McpServer.Tool --version x.y.z

Run:

axsg-mcp --workspace /Users/wieslawsoltes/GitHub/XamlToCSharpGenerator

For repo development:

dotnet run --project src/XamlToCSharpGenerator.McpServer -- --workspace /Users/wieslawsoltes/GitHub/XamlToCSharpGenerator

Query model

The workspace host is query-oriented.

Use this rule:

  • tools/call or resources/read
  • poll after workspace or editor changes
  • do not expect live subscriptions into a running app

The host does expose the same runtime-shaped snapshot resources as the shared catalog, but on the standalone workspace tool those are only snapshots of the tool process itself. They are not a live bridge into a separate Avalonia runtime.

Workspace MCP tools

Preview planning

  • axsg.preview.projectContext

Metadata and projections

  • axsg.workspace.metadataDocument
  • axsg.workspace.inlineCSharpProjections

Cross-language navigation

  • axsg.workspace.csharpReferences
  • axsg.workspace.csharpDeclarations

Rename planning and edits

  • axsg.workspace.renamePropagation
  • axsg.workspace.prepareRename
  • axsg.workspace.rename

Preview project context

Use axsg.preview.projectContext when a client needs to know which project and project-relative path the preview system should use.

Example:

{
  "jsonrpc": "2.0",
  "id": 10,
  "method": "tools/call",
  "params": {
    "name": "axsg.preview.projectContext",
    "arguments": {
      "uri": "file:///Users/wieslawsoltes/GitHub/XamlToCSharpGenerator/samples/ControlCatalog/Pages/ListBoxPage.xaml",
      "workspaceRoot": "/Users/wieslawsoltes/GitHub/XamlToCSharpGenerator"
    }
  }
}

Typical response fields include:

  • projectPath
  • targetPath
  • projectRelativeXamlPath
  • targetFramework

Use this before you start a preview session from a custom client.

Metadata-as-source

Use axsg.workspace.metadataDocument when you already have either:

  • an AXSG metadata document id
  • an AXSG metadata URI

Example:

{
  "jsonrpc": "2.0",
  "id": 11,
  "method": "tools/call",
  "params": {
    "name": "axsg.workspace.metadataDocument",
    "arguments": {
      "metadataUri": "axsg-metadata://document?id=ExternalControl"
    }
  }
}

Response shape:

{
  "text": "namespace ExternalLibrary { public partial class ExternalControl : UserControl { ... } }"
}

Inline C# projections

Use axsg.workspace.inlineCSharpProjections when a custom editor or tool needs the synthetic C# documents derived from inline AXSG code regions.

Example:

{
  "jsonrpc": "2.0",
  "id": 12,
  "method": "tools/call",
  "params": {
    "name": "axsg.workspace.inlineCSharpProjections",
    "arguments": {
      "uri": "file:///Users/wieslawsoltes/GitHub/XamlToCSharpGenerator/samples/SourceGenXamlCatalogSample/Pages/InlineCodeCDataPage.axaml",
      "workspaceRoot": "/Users/wieslawsoltes/GitHub/XamlToCSharpGenerator",
      "documentText": "<UserControl ... />",
      "version": 7
    }
  }
}

Each projection item includes:

  • id
  • kind
  • xamlRange
  • projectedCodeRange
  • projectedText

Use documentText when the client has unsaved in-memory edits and wants projection results against that text instead of the file on disk.

C# to XAML references and declarations

References

Use axsg.workspace.csharpReferences to map a C# symbol position back to XAML references.

{
  "jsonrpc": "2.0",
  "id": 13,
  "method": "tools/call",
  "params": {
    "name": "axsg.workspace.csharpReferences",
    "arguments": {
      "uri": "file:///Users/wieslawsoltes/GitHub/XamlToCSharpGenerator/samples/ControlCatalog/ViewModels/ListBoxPageViewModel.cs",
      "line": 12,
      "character": 18,
      "workspaceRoot": "/Users/wieslawsoltes/GitHub/XamlToCSharpGenerator"
    }
  }
}

Each result includes:

  • uri
  • range
  • isDeclaration

Declarations

Use axsg.workspace.csharpDeclarations when you want the XAML declaration side instead.

The arguments match the references tool:

  • uri
  • line
  • character
  • optional workspaceRoot
  • optional documentText

Rename planning and rename edits

axsg.workspace.prepareRename

Use this first when your client needs to know whether rename is valid at a XAML position.

Response:

  • range
  • placeholder

axsg.workspace.renamePropagation

Use this when rename started from C# and you only need the XAML-side workspace edit.

axsg.workspace.rename

Use this when rename starts from a XAML position and you want the full AXSG rename edit payload.

Example:

{
  "jsonrpc": "2.0",
  "id": 14,
  "method": "tools/call",
  "params": {
    "name": "axsg.workspace.rename",
    "arguments": {
      "uri": "file:///Users/wieslawsoltes/GitHub/XamlToCSharpGenerator/samples/ControlCatalog/Pages/ListBoxPage.xaml",
      "line": 2,
      "character": 16,
      "newName": "ItemsPanelView",
      "workspaceRoot": "/Users/wieslawsoltes/GitHub/XamlToCSharpGenerator"
    }
  }
}

The tool returns a workspace-edit payload with URI-keyed text changes. That result is designed for AI tools and custom editors that want the rename plan without speaking LSP directly.

Suggested client workflows

Preview launch planning

  1. call axsg.preview.projectContext
  2. start preview using the resolved project and relative XAML path

Custom editor inline-code analysis

  1. call axsg.workspace.inlineCSharpProjections with the in-memory documentText
  2. render diagnostics or semantic overlays against the projection mapping

Cross-language rename from C#

  1. call axsg.workspace.renamePropagation
  2. apply only the returned XAML edit set

XAML rename workflow

  1. call axsg.workspace.prepareRename
  2. if valid, call axsg.workspace.rename
  3. apply the resulting workspace edit

Polling guidance

Because the workspace host is not a live runtime host, use explicit polling:

  • after file saves
  • after editor buffer changes that matter to your query
  • after project/solution reload

Use the runtime host instead when the question is about:

  • live hot reload state
  • live hot design workspace state
  • studio session state