fix: treat empty title and body as explicit input in issue_write

README.md

@@ -1022,7 +1022,7 @@ For negotiated supported protocol versions `2026-07-28` or newer, the consolidat
   - **OAuth Challenge Scopes**: `repo`
   - **MCP App UI**: `ui://github-mcp-server/issue-write`
   - `assignees`: Usernames to assign to this issue (string[], optional)
-  - `body`: Issue body content (string, optional)
+  - `body`: Issue body content. For 'update', an empty string clears the body; omit body to keep it unchanged. (string, optional)
   - `duplicate_of`: Issue number that this issue is a duplicate of. Required when state_reason is 'duplicate'. (number, optional)
   - `issue_fields`: Issue field values to set or clear. Each item requires 'field_name' and exactly one of 'value', 'field_option_name', or 'delete: true'. (object[], optional)
   - `issue_number`: Issue number to update (number, optional)
@@ -1040,7 +1040,7 @@ For negotiated supported protocol versions `2026-07-28` or newer, the consolidat
   - `repo`: Repository name (string, required)
   - `state`: New state (string, optional)
   - `state_reason`: Reason for the state change. Ignored unless state is changed. (string, optional)
-  - `title`: Issue title (string, optional)
+  - `title`: Issue title. Required for 'create'. For 'update', an empty string is rejected; omit title to keep it unchanged. (string, optional)
   - `type`: Type of this issue. For updates, pass null to remove the current type. Only use if issue types are enabled for this repository. Use list_issue_types to get valid type values for this repository or its owner organization. If the repository doesn't support issue types, omit this parameter. (string | null, optional)
 
 - **list_issue_fields** - List issue fields

pkg/github/__toolsnaps__/issue_write.snap

@@ -24,7 +24,7 @@
         "type": "array"
       },
       "body": {
-        "description": "Issue body content",
+        "description": "Issue body content. For 'update', an empty string clears the body; omit body to keep it unchanged.",
         "type": "string"
       },
       "duplicate_of": {
@@ -126,7 +126,7 @@
         "type": "string"
       },
       "title": {
-        "description": "Issue title",
+        "description": "Issue title. Required for 'create'. For 'update', an empty string is rejected; omit title to keep it unchanged.",
         "type": "string"
       },
       "type": {

pkg/github/issues.go

@@ -2746,11 +2746,11 @@ Options are:
 					},
 					"title": {
 						Type:        "string",
-						Description: "Issue title",
+						Description: "Issue title. Required for 'create'. For 'update', an empty string is rejected; omit title to keep it unchanged.",
 					},
 					"body": {
 						Type:        "string",
-						Description: "Issue body content",
+						Description: "Issue body content. For 'update', an empty string clears the body; omit body to keep it unchanged.",
 					},
 					"assignees": {
 						Type:        "array",
@@ -2883,12 +2883,16 @@ Options are:
 			if err != nil {
 				return utils.NewToolResultError(err.Error()), nil, nil
 			}
+			titleValue, titleProvided := args["title"]
+			titleProvided = titleProvided && titleValue != nil
 
 			// Optional parameters
 			body, err := OptionalParam[string](args, "body")
 			if err != nil {
 				return utils.NewToolResultError(err.Error()), nil, nil
 			}
+			bodyValue, bodyProvided := args["body"]
+			bodyProvided = bodyProvided && bodyValue != nil
 
 			// Get assignees
 			assignees, err := OptionalStringArrayParam(args, "assignees")
@@ -3017,6 +3021,8 @@ Options are:
 					AssigneesProvided: assigneesProvided,
 					LabelsProvided:    labelsProvided,
 					IssueTypeProvided: issueTypeProvided,
+					TitleProvided:     titleProvided,
+					BodyProvided:      bodyProvided,
 				}))
 			default:
 				return utils.NewToolResultError("invalid method, must be either 'create' or 'update'"), nil, nil
@@ -3385,6 +3391,11 @@ type UpdateIssueOptions struct {
 	LabelsProvided bool
 	// IssueTypeProvided sends the type field, including an explicit clear.
 	IssueTypeProvided bool
+	// TitleProvided sends the title field, including an explicitly empty value.
+	// An empty title is rejected before the request is sent.
+	TitleProvided bool
+	// BodyProvided sends the body field, so an empty string clears the body.
+	BodyProvided bool
 }
 
 func UpdateIssue(ctx context.Context, client *github.Client, gqlClient *githubv4.Client, owner string, repo string, issueNumber int, title string, body string, assignees []string, labels []string, milestoneNum int, issueType string, issueFieldValues []*github.IssueRequestFieldValue, fieldIDsToDelete []int64, state string, stateReason string, duplicateOf int, opts ...UpdateIssueOptions) (*mcp.CallToolResult, error) {
@@ -3406,17 +3417,25 @@ func updateIssue(ctx context.Context, client *github.Client, gqlClient *githubv4
 		updateOptions.AssigneesProvided = updateOptions.AssigneesProvided || opt.AssigneesProvided
 		updateOptions.LabelsProvided = updateOptions.LabelsProvided || opt.LabelsProvided
 		updateOptions.IssueTypeProvided = updateOptions.IssueTypeProvided || opt.IssueTypeProvided
+		updateOptions.TitleProvided = updateOptions.TitleProvided || opt.TitleProvided
+		updateOptions.BodyProvided = updateOptions.BodyProvided || opt.BodyProvided
 	}
 
 	// Create the issue request with only provided fields
 	issueRequest := github.UpdateIssueRequest{}
 
-	// Set optional parameters if provided
-	if title != "" {
+	// Set optional parameters if provided. An empty body is meaningful (it
+	// clears the body), and an empty title is rejected rather than treated as
+	// "not provided", so both are decided by presence, not by value.
+	if updateOptions.TitleProvided && title == "" {
+		return utils.NewToolResultError("title cannot be empty, omit it to keep the current title"), nil, nil
+	}
+
+	if title != "" || updateOptions.TitleProvided {
 		issueRequest.Title = new(title)
 	}
 
-	if body != "" {
+	if body != "" || updateOptions.BodyProvided {
 		issueRequest.Body = new(body)
 	}
 

pkg/github/issues_test.go

@@ -5252,6 +5252,69 @@ func Test_UpdateIssueClearsLabelsAndAssignees(t *testing.T) {
 	assert.Equal(t, updatedIssue.GetHTMLURL(), updateResp.URL)
 }
 
+func Test_UpdateIssueClearsBodyWhenExplicitlyEmpty(t *testing.T) {
+	serverTool := IssueWrite(translations.NullTranslationHelper)
+	updatedIssue := &github.Issue{
+		Number:  new(8),
+		HTMLURL: new("https://github.com/owner/repo/issues/8"),
+	}
+
+	client := mustNewGHClient(t, MockHTTPClientWithHandlers(map[string]http.HandlerFunc{
+		PatchReposIssuesByOwnerByRepoByIssueNumber: expectRequestBody(t, map[string]any{
+			"body": "",
+		}).andThen(mockResponse(t, http.StatusOK, updatedIssue)),
+	}))
+	gqlClient := githubv4.NewClient(githubv4mock.NewMockedHTTPClient())
+	deps := BaseDeps{
+		Client:    client,
+		GQLClient: gqlClient,
+	}
+	handler := serverTool.Handler(deps)
+
+	request := createMCPRequest(map[string]any{
+		"method":       "update",
+		"owner":        "owner",
+		"repo":         "repo",
+		"issue_number": float64(8),
+		"body":         "",
+	})
+	result, err := handler(ContextWithDeps(context.Background(), deps), &request)
+
+	require.NoError(t, err)
+	if result.IsError {
+		t.Fatalf("Unexpected error result: %s", getErrorResult(t, result).Text)
+	}
+	textContent := getTextResult(t, result)
+
+	var updateResp MinimalResponse
+	require.NoError(t, json.Unmarshal([]byte(textContent.Text), &updateResp))
+	assert.Equal(t, updatedIssue.GetHTMLURL(), updateResp.URL)
+}
+
+func Test_UpdateIssueRejectsExplicitlyEmptyTitle(t *testing.T) {
+	serverTool := IssueWrite(translations.NullTranslationHelper)
+	client := mustNewGHClient(t, MockHTTPClientWithHandlers(map[string]http.HandlerFunc{}))
+	gqlClient := githubv4.NewClient(githubv4mock.NewMockedHTTPClient())
+	deps := BaseDeps{
+		Client:    client,
+		GQLClient: gqlClient,
+	}
+	handler := serverTool.Handler(deps)
+
+	request := createMCPRequest(map[string]any{
+		"method":       "update",
+		"owner":        "owner",
+		"repo":         "repo",
+		"issue_number": float64(8),
+		"title":        "",
+	})
+	result, err := handler(ContextWithDeps(context.Background(), deps), &request)
+
+	require.NoError(t, err)
+	require.True(t, result.IsError, "an explicitly empty title must be rejected instead of silently ignored")
+	assert.Contains(t, getErrorResult(t, result).Text, "title cannot be empty")
+}
+
 func Test_ParseISOTimestamp(t *testing.T) {
 	tests := []struct {
 		name         string