fix: clarify issue comment update contract

Reject explicitly empty comment bodies at runtime and distinguish issue and pull request conversation comments from pull request review comments in the tool schema and generated docs.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 9acf9c83-49aa-41af-a42d-ad75de34d132

Author: timrogers

README.md

@@ -1060,7 +1060,7 @@ The following sets of tools are available:
 - **update_issue_comment** - Update issue comment
   - **OAuth Challenge Scopes**: `repo`
   - `body`: New comment content (string, required)
-  - `comment_id`: The numeric ID of the issue or pull request comment to update (integer, required)
+  - `comment_id`: The numeric ID of the issue or pull request conversation comment to update. Do not use a pull request review comment ID. (integer, required)
   - `owner`: Repository owner (string, required)
   - `repo`: Repository name (string, required)
 

pkg/github/__toolsnaps__/update_issue_comment.snap

@@ -4,7 +4,7 @@
     "readOnlyHint": false,
     "title": "Update issue comment"
   },
-  "description": "Update the body of an existing issue or pull request comment.",
+  "description": "Update the body of an existing issue or pull request conversation comment. This tool cannot update pull request review comments.",
   "inputSchema": {
     "properties": {
       "body": {
@@ -13,7 +13,7 @@
         "type": "string"
       },
       "comment_id": {
-        "description": "The numeric ID of the issue or pull request comment to update",
+        "description": "The numeric ID of the issue or pull request conversation comment to update. Do not use a pull request review comment ID.",
         "minimum": 1,
         "type": "integer"
       },

pkg/github/issues.go

@@ -1552,13 +1552,13 @@ func AddIssueComment(t translations.TranslationHelperFunc) inventory.ServerTool
 		})
 }
 
-// UpdateIssueComment creates a tool to update an issue or pull request comment.
+// UpdateIssueComment creates a tool to update an issue or pull request conversation comment.
 func UpdateIssueComment(t translations.TranslationHelperFunc) inventory.ServerTool {
 	return NewTool(
 		ToolsetMetadataIssues,
 		mcp.Tool{
 			Name:        "update_issue_comment",
-			Description: t("TOOL_UPDATE_ISSUE_COMMENT_DESCRIPTION", "Update the body of an existing issue or pull request comment."),
+			Description: t("TOOL_UPDATE_ISSUE_COMMENT_DESCRIPTION", "Update the body of an existing issue or pull request conversation comment. This tool cannot update pull request review comments."),
 			Annotations: &mcp.ToolAnnotations{
 				Title:        t("TOOL_UPDATE_ISSUE_COMMENT_USER_TITLE", "Update issue comment"),
 				ReadOnlyHint: false,
@@ -1576,7 +1576,7 @@ func UpdateIssueComment(t translations.TranslationHelperFunc) inventory.ServerTo
 					},
 					"comment_id": {
 						Type:        "integer",
-						Description: "The numeric ID of the issue or pull request comment to update",
+						Description: "The numeric ID of the issue or pull request conversation comment to update. Do not use a pull request review comment ID.",
 						Minimum:     jsonschema.Ptr(1.0),
 					},
 					"body": {
@@ -1605,10 +1605,16 @@ func UpdateIssueComment(t translations.TranslationHelperFunc) inventory.ServerTo
 			if commentID < 1 {
 				return utils.NewToolResultError("comment_id must be greater than 0"), nil, nil
 			}
-			body, err := RequiredParam[string](args, "body")
+			body, hasBody, err := OptionalParamOK[string](args, "body")
 			if err != nil {
 				return utils.NewToolResultError(err.Error()), nil, nil
 			}
+			if !hasBody {
+				return utils.NewToolResultError("missing required parameter: body"), nil, nil
+			}
+			if body == "" {
+				return utils.NewToolResultError("body cannot be empty when provided"), nil, nil
+			}
 
 			client, err := deps.GetClient(ctx)
 			if err != nil {

pkg/github/issues_test.go

@@ -6751,6 +6751,17 @@ func TestUpdateIssueCommentHandler(t *testing.T) {
 			expectToolError:    true,
 			expectedToolErrMsg: "missing required parameter: body",
 		},
+		{
+			name: "empty body",
+			requestArgs: map[string]any{
+				"owner":      "owner",
+				"repo":       "repo",
+				"comment_id": float64(456),
+				"body":       "",
+			},
+			expectToolError:    true,
+			expectedToolErrMsg: "body cannot be empty when provided",
+		},
 		{
 			name: "negative comment ID",
 			requestArgs: map[string]any{