add_member

[refactoring]

Inserts a member (method, property, field, event, or constructor) into an existing type from C# source, and returns a diff. The member text is parsed and validated before it is inserted, and only the inserted code is formatted, so the change lands indented in the body without reformatting the rest of the file. For a partial type, filePath chooses which part receives the member; by default the largest non-generated part is used.

Why this tool exists

C# refactors are semantic operations, not search-and-replace operations.

How it helps the agent

The model can preview or apply semantic changes while preserving symbol identity across overloads, files, and projects.

Try it locally in the Glider playground

Parameters

Name	Type	Required	Description
containerName	string	Yes	The type to add the member to. A stable symbolKey (preferred) or a name (simple or fully qualified).
memberCode	string	Yes	The full C# source of the member to insert.
filePath	string	No	For a partial type, the file whose part receives the member. Absolute or loaded-root-relative. Defaults to the largest non-generated part.
projectName	string	No	Optional project name to limit search when finding the type by name.
applyChanges	boolean	No	If true (default), applies changes to disk. If false, returns a preview diff.
failOnErrors	boolean	No	If true, do not write when the edit introduces a compile error; the response reports the diagnostics.
includeDiff	boolean	No	Include unified diff in response. Default is true.
maxDiffChars	number	No	Max diff characters. Use 0 for unlimited. Default is 50000.
includePerFileDiff	boolean	No	Include per-file diffs in changedFiles. Default is true.
pathStyle	string	No	Path style: 'absolute' (default) or 'relative' (to solution root).

Examples

Preview adding a method to a class

Request 
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "add_member",
    "arguments": {
      "containerName": "OrderService",
      "memberCode": "public decimal Total() => 0m;",
      "applyChanges": false
    }
  }
}

Response 
{
  "success": true,
  "data": {
    "containerName": "MyProject.OrderService",
    "memberName": "Total",
    "memberKind": "Method",
    "filePath": "/path/to/OrderService.cs",
    "filesChanged": 1,
    "applied": false,
    "message": null,
    "diagnostics": {
      "errorCount": 0,
      "warningCount": 0,
      "items": []
    },
    "unifiedDiff": "...",
    "changedFiles": [
      {
        "filePath": "/path/to/OrderService.cs",
        "changeCount": 1,
        "diff": "..."
      }
    ]
  },
  "error": null
}

Response Notes

Returns a unified diff of the insertion. containerName, memberName, and memberKind identify what was added, and filePath names the file that received it (the chosen part for a partial type). diagnostics reports the compile errors and warnings the inserted member introduces; when failOnErrors is true and it introduces an error, applied is false and message explains why. When the file is linked into several projects or targets, the check spans all of them.