diff --git a/docs/feature-flags.md b/docs/feature-flags.md
index 590cb6597..08f59b64c 100644
--- a/docs/feature-flags.md
+++ b/docs/feature-flags.md
@@ -75,7 +75,7 @@ runtime behavior (such as output formatting) won't appear here.
   - `type`: Type of this issue. Only use if issue types are enabled for this repository. Use list_issue_types tool to get valid type values for this repository or its owner organization. If the repository doesn't support issue types, omit this parameter. (string, optional)
 
 - **ui_get** - Get UI data
-  - **Required OAuth Scopes**: `repo`, `read:org`
+  - **Required OAuth Scopes (any of)**: `repo`, `read:org`
   - **Accepted OAuth Scopes**: `admin:org`, `read:org`, `repo`, `write:org`
   - `method`: The type of data to fetch (string, required)
   - `owner`: Repository owner (required for all methods) (string, required)
@@ -99,7 +99,7 @@ runtime behavior (such as output formatting) won't appear here.
 
 - **issue_write** - Create or update issue/pull request
   - **Required OAuth Scopes**: `repo`
-  - `assignees`: Usernames to assign to this issue (string[], optional)
+  - `assignees`: Usernames to assign to this issue. ([], optional)
   - `body`: Issue body content (string, optional)
   - `duplicate_of`: Issue number that this issue is a duplicate of. Only used 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)
diff --git a/docs/insiders-features.md b/docs/insiders-features.md
index 3306b5cd8..f1e56db96 100644
--- a/docs/insiders-features.md
+++ b/docs/insiders-features.md
@@ -69,7 +69,7 @@ The list below is generated from the Go source. It covers tool **inventory and s
   - `type`: Type of this issue. Only use if issue types are enabled for this repository. Use list_issue_types tool to get valid type values for this repository or its owner organization. If the repository doesn't support issue types, omit this parameter. (string, optional)
 
 - **ui_get** - Get UI data
-  - **Required OAuth Scopes**: `repo`, `read:org`
+  - **Required OAuth Scopes (any of)**: `repo`, `read:org`
   - **Accepted OAuth Scopes**: `admin:org`, `read:org`, `repo`, `write:org`
   - `method`: The type of data to fetch (string, required)
   - `owner`: Repository owner (required for all methods) (string, required)
@@ -93,7 +93,7 @@ The list below is generated from the Go source. It covers tool **inventory and s
 
 - **issue_write** - Create or update issue/pull request
   - **Required OAuth Scopes**: `repo`
-  - `assignees`: Usernames to assign to this issue (string[], optional)
+  - `assignees`: Usernames to assign to this issue. ([], optional)
   - `body`: Issue body content (string, optional)
   - `duplicate_of`: Issue number that this issue is a duplicate of. Only used 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)
diff --git a/pkg/github/__toolsnaps__/issue_write_ff_remote_mcp_issue_fields.snap b/pkg/github/__toolsnaps__/issue_write_ff_remote_mcp_issue_fields.snap
index 47d00c445..23973184b 100644
--- a/pkg/github/__toolsnaps__/issue_write_ff_remote_mcp_issue_fields.snap
+++ b/pkg/github/__toolsnaps__/issue_write_ff_remote_mcp_issue_fields.snap
@@ -15,9 +15,44 @@
   "inputSchema": {
     "properties": {
       "assignees": {
-        "description": "Usernames to assign to this issue",
+        "description": "Usernames to assign to this issue.",
         "items": {
-          "type": "string"
+          "oneOf": [
+            {
+              "description": "GitHub username",
+              "type": "string"
+            },
+            {
+              "properties": {
+                "confidence": {
+                  "description": "How confident you are in this choice. Use 'HIGH' for clear signal or explicit user request, 'MEDIUM' for reasonable inference with some ambiguity, 'LOW' for best guess with limited signal.",
+                  "enum": [
+                    "LOW",
+                    "MEDIUM",
+                    "HIGH"
+                  ],
+                  "type": "string"
+                },
+                "is_suggestion": {
+                  "description": "If true, this assignee is sent to the API as a suggestion (suggest:true) rather than a direct assignment. Whether the assignee is applied or recorded as a proposal is determined by the API.",
+                  "type": "boolean"
+                },
+                "login": {
+                  "description": "GitHub username",
+                  "type": "string"
+                },
+                "rationale": {
+                  "description": "One concise sentence explaining why this person is the right assignee. State the concrete signal (e.g. 'Owns the auth module where the bug was reported').",
+                  "maxLength": 280,
+                  "type": "string"
+                }
+              },
+              "required": [
+                "login"
+              ],
+              "type": "object"
+            }
+          ]
         },
         "type": "array"
       },
diff --git a/pkg/github/issues.go b/pkg/github/issues.go
index f98982f1e..e9cf64334 100644
--- a/pkg/github/issues.go
+++ b/pkg/github/issues.go
@@ -1913,9 +1913,37 @@ Options are:
 					},
 					"assignees": {
 						Type:        "array",
-						Description: "Usernames to assign to this issue",
+						Description: "Usernames to assign to this issue.",
 						Items: &jsonschema.Schema{
-							Type: "string",
+							OneOf: []*jsonschema.Schema{
+								{Type: "string", Description: "GitHub username"},
+								{
+									Type: "object",
+									Properties: map[string]*jsonschema.Schema{
+										"login": {
+											Type:        "string",
+											Description: "GitHub username",
+										},
+										"rationale": {
+											Type: "string",
+											Description: "One concise sentence explaining why this person is the right assignee. " +
+												"State the concrete signal (e.g. 'Owns the auth module where the bug was reported').",
+											MaxLength: jsonschema.Ptr(280),
+										},
+										"confidence": {
+											Type:        "string",
+											Description: "How confident you are in this choice. Use 'HIGH' for clear signal or explicit user request, 'MEDIUM' for reasonable inference with some ambiguity, 'LOW' for best guess with limited signal.",
+											Enum:        []any{"LOW", "MEDIUM", "HIGH"},
+										},
+										"is_suggestion": {
+											Type: "boolean",
+											Description: "If true, this assignee is sent to the API as a suggestion (suggest:true) rather than a direct assignment. " +
+												"Whether the assignee is applied or recorded as a proposal is determined by the API.",
+										},
+									},
+									Required: []string{"login"},
+								},
+							},
 						},
 					},
 					"labels": {
@@ -2049,8 +2077,8 @@ Options are:
 				return utils.NewToolResultError(err.Error()), nil, nil
 			}
 
-			// Get assignees
-			assignees, err := OptionalStringArrayParam(args, "assignees")
+			// Get assignees (polymorphic: string or object with login/rationale/confidence/is_suggestion)
+			assignees, assigneesPayload, useAssigneeObjectForm, err := parsePolymorphicAssignees(args)
 			if err != nil {
 				return utils.NewToolResultError(err.Error()), nil, nil
 			}
@@ -2129,16 +2157,45 @@ Options are:
 			switch method {
 			case "create":
 				result, err := CreateIssue(ctx, client, owner, repo, title, body, assignees, labels, milestoneNum, issueType, issueFieldValues)
+				if err != nil || result.IsError {
+					return result, nil, err
+				}
+				// If object-form assignees were used on create, apply them via a follow-up PATCH
+				if useAssigneeObjectForm {
+					textContent, ok := result.Content[0].(*mcp.TextContent)
+					if ok {
+						var created MinimalResponse
+						if jsonErr := json.Unmarshal([]byte(textContent.Text), &created); jsonErr == nil {
+							if issueNum, parseErr := parseIssueNumberFromURL(created.URL); parseErr == nil {
+								return patchAssigneesWithIntent(ctx, client, owner, repo, issueNum, assigneesPayload)
+							}
+						}
+					}
+				}
 				return result, nil, err
 			case "update":
 				issueNumber, err := RequiredInt(args, "issue_number")
 				if err != nil {
 					return utils.NewToolResultError(err.Error()), nil, nil
 				}
-				result, err := UpdateIssue(ctx, client, gqlClient, owner, repo, issueNumber, title, body, assignees, labels, milestoneNum, issueType, issueFieldValues, fieldIDsToDelete, state, stateReason, duplicateOf, UpdateIssueOptions{
-					AssigneesProvided: assigneesProvided,
+				// When object-form assignees are used, skip assignees in the standard
+				// UpdateIssue call and apply them via a separate PATCH with intent metadata.
+				updateAssignees := assignees
+				updateAssigneesProvided := assigneesProvided
+				if useAssigneeObjectForm {
+					updateAssignees = nil
+					updateAssigneesProvided = false
+				}
+				result, err := UpdateIssue(ctx, client, gqlClient, owner, repo, issueNumber, title, body, updateAssignees, labels, milestoneNum, issueType, issueFieldValues, fieldIDsToDelete, state, stateReason, duplicateOf, UpdateIssueOptions{
+					AssigneesProvided: updateAssigneesProvided,
 					LabelsProvided:    labelsProvided,
 				})
+				if err != nil || result.IsError {
+					return result, nil, err
+				}
+				if useAssigneeObjectForm {
+					return patchAssigneesWithIntent(ctx, client, owner, repo, issueNumber, assigneesPayload)
+				}
 				return result, nil, err
 			default:
 				return utils.NewToolResultError("invalid method, must be either 'create' or 'update'"), nil, nil
@@ -2452,6 +2509,125 @@ type UpdateIssueOptions struct {
 	LabelsProvided bool
 }
 
+// assigneeWithIntent represents the object form of an assignee entry, allowing a
+// rationale, confidence level, and/or suggest flag to be sent alongside the login.
+type assigneeWithIntent struct {
+	Login      string `json:"login"`
+	Rationale  string `json:"rationale,omitempty"`
+	Confidence string `json:"confidence,omitempty"`
+	Suggest    bool   `json:"suggest,omitempty"`
+}
+
+// assigneesUpdateRequest is a custom request body for updating an issue's assignees
+// where individual assignees may optionally include a rationale. Each element of
+// Assignees is either a string (login) or an assigneeWithIntent object.
+type assigneesUpdateRequest struct {
+	Assignees []any `json:"assignees"`
+}
+
+// parsePolymorphicAssignees parses the assignees parameter, which may be an array
+// of strings or an array of objects with login, rationale, confidence, is_suggestion.
+// Returns the plain login strings, the polymorphic payload, and whether object form is used.
+func parsePolymorphicAssignees(args map[string]any) ([]string, []any, bool, error) {
+	assigneesRaw, ok := args["assignees"]
+	if !ok || assigneesRaw == nil {
+		return []string{}, nil, false, nil
+	}
+	assigneesSlice, ok := assigneesRaw.([]any)
+	if !ok {
+		if strs, ok := assigneesRaw.([]string); ok {
+			assigneesSlice = make([]any, len(strs))
+			for i, s := range strs {
+				assigneesSlice[i] = s
+			}
+		} else {
+			return nil, nil, false, fmt.Errorf("parameter assignees must be an array")
+		}
+	}
+
+	useObjectForm := false
+	logins := make([]string, 0, len(assigneesSlice))
+	payload := make([]any, 0, len(assigneesSlice))
+	for _, item := range assigneesSlice {
+		switch v := item.(type) {
+		case string:
+			logins = append(logins, v)
+			payload = append(payload, v)
+		case map[string]any:
+			login, err := RequiredParam[string](v, "login")
+			if err != nil {
+				return nil, nil, false, fmt.Errorf("each assignee object must have a 'login' string")
+			}
+			logins = append(logins, login)
+			rationale, err := OptionalParam[string](v, "rationale")
+			if err != nil {
+				return nil, nil, false, err
+			}
+			rationale = strings.TrimSpace(rationale)
+			if len([]rune(rationale)) > 280 {
+				return nil, nil, false, fmt.Errorf("assignee rationale must be 280 characters or less")
+			}
+			confidence, err := OptionalParam[string](v, "confidence")
+			if err != nil {
+				return nil, nil, false, err
+			}
+			confidence = normalizeConfidence(confidence)
+			if confidence != "" && confidence != "LOW" && confidence != "MEDIUM" && confidence != "HIGH" {
+				return nil, nil, false, fmt.Errorf("confidence must be one of: LOW, MEDIUM, HIGH")
+			}
+			isSuggestion, err := OptionalParam[bool](v, "is_suggestion")
+			if err != nil {
+				return nil, nil, false, err
+			}
+			if rationale == "" && !isSuggestion && confidence == "" {
+				payload = append(payload, login)
+			} else {
+				useObjectForm = true
+				payload = append(payload, assigneeWithIntent{Login: login, Rationale: rationale, Confidence: confidence, Suggest: isSuggestion})
+			}
+		default:
+			return nil, nil, false, fmt.Errorf("each assignee must be a string or an object with 'login' and optional 'rationale', 'confidence', and/or 'is_suggestion'")
+		}
+	}
+	return logins, payload, useObjectForm, nil
+}
+
+// patchAssigneesWithIntent sends a PATCH request with object-form assignees
+// that include rationale, confidence, and/or suggest metadata.
+func patchAssigneesWithIntent(ctx context.Context, client *github.Client, owner, repo string, issueNumber int, assigneesPayload []any) (*mcp.CallToolResult, any, error) {
+	body := &assigneesUpdateRequest{Assignees: assigneesPayload}
+	apiURL := fmt.Sprintf("repos/%s/%s/issues/%d", owner, repo, issueNumber)
+	req, err := client.NewRequest(ctx, "PATCH", apiURL, body)
+	if err != nil {
+		return utils.NewToolResultErrorFromErr("failed to create request", err), nil, nil
+	}
+
+	issue := &github.Issue{}
+	resp, err := client.Do(req, issue)
+	if err != nil {
+		return ghErrors.NewGitHubAPIErrorResponse(ctx, "failed to update issue assignees", resp, err), nil, nil
+	}
+	defer func() { _ = resp.Body.Close() }()
+
+	r, err := json.Marshal(MinimalResponse{
+		ID:  fmt.Sprintf("%d", issue.GetID()),
+		URL: issue.GetHTMLURL(),
+	})
+	if err != nil {
+		return utils.NewToolResultErrorFromErr("failed to marshal response", err), nil, nil
+	}
+	return utils.NewToolResultText(string(r)), nil, nil
+}
+
+// parseIssueNumberFromURL extracts the issue number from a GitHub issue URL.
+func parseIssueNumberFromURL(url string) (int, error) {
+	parts := strings.Split(url, "/")
+	if len(parts) == 0 {
+		return 0, fmt.Errorf("invalid issue URL: %s", url)
+	}
+	return strconv.Atoi(parts[len(parts)-1])
+}
+
 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) {
 	updateOptions := UpdateIssueOptions{
 		AssigneesProvided: len(assignees) > 0,
diff --git a/pkg/github/issues_test.go b/pkg/github/issues_test.go
index 5775daf37..4402b3234 100644
--- a/pkg/github/issues_test.go
+++ b/pkg/github/issues_test.go
@@ -3484,6 +3484,242 @@ func Test_LegacyUpdateIssueClearsLabelsAndAssignees(t *testing.T) {
 	assert.Equal(t, updatedIssue.GetHTMLURL(), updateResp.URL)
 }
 
+func Test_UpdateIssueWithAssigneeRationale(t *testing.T) {
+	serverTool := IssueWrite(translations.NullTranslationHelper)
+
+	mockIssue := &github.Issue{
+		Number:  github.Ptr(42),
+		HTMLURL: github.Ptr("https://github.com/owner/repo/issues/42"),
+	}
+
+	tests := []struct {
+		name             string
+		mockedRESTClient *http.Client
+		requestArgs      map[string]any
+		expectError      bool
+		expectedErrMsg   string
+	}{
+		{
+			name: "update with object-form assignees sends intent metadata",
+			mockedRESTClient: func() *http.Client {
+				callCount := 0
+				return MockHTTPClientWithHandlers(map[string]http.HandlerFunc{
+					PatchReposIssuesByOwnerByRepoByIssueNumber: func(w http.ResponseWriter, r *http.Request) {
+						callCount++
+						var body map[string]any
+						require.NoError(t, json.NewDecoder(r.Body).Decode(&body))
+						if callCount == 1 {
+							// First call: UpdateIssue without assignees
+							require.NotContains(t, body, "assignees", "first PATCH should not contain assignees")
+							require.Equal(t, "Updated Title", body["title"])
+						} else {
+							// Second call: patchAssigneesWithIntent
+							assignees, ok := body["assignees"].([]any)
+							require.True(t, ok, "second PATCH should contain assignees array")
+							require.Len(t, assignees, 2)
+
+							a0, ok := assignees[0].(map[string]any)
+							require.True(t, ok)
+							assert.Equal(t, "octocat", a0["login"])
+							assert.Equal(t, "Owns the auth module", a0["rationale"])
+							assert.Equal(t, true, a0["suggest"])
+
+							a1, ok := assignees[1].(string)
+							require.True(t, ok)
+							assert.Equal(t, "user2", a1)
+						}
+						w.WriteHeader(http.StatusOK)
+						respBytes, _ := json.Marshal(mockIssue)
+						_, _ = w.Write(respBytes)
+					},
+				})
+			}(),
+			requestArgs: map[string]any{
+				"method":       "update",
+				"owner":        "owner",
+				"repo":         "repo",
+				"issue_number": float64(42),
+				"title":        "Updated Title",
+				"assignees": []any{
+					map[string]any{
+						"login":         "octocat",
+						"rationale":     "Owns the auth module",
+						"is_suggestion": true,
+					},
+					"user2",
+				},
+			},
+		},
+		{
+			name: "update with plain string assignees uses standard path",
+			mockedRESTClient: MockHTTPClientWithHandlers(map[string]http.HandlerFunc{
+				PatchReposIssuesByOwnerByRepoByIssueNumber: expectRequestBody(t, map[string]any{
+					"assignees": []any{"user1", "user2"},
+				}).andThen(
+					mockResponse(t, http.StatusOK, mockIssue),
+				),
+			}),
+			requestArgs: map[string]any{
+				"method":       "update",
+				"owner":        "owner",
+				"repo":         "repo",
+				"issue_number": float64(42),
+				"assignees":    []any{"user1", "user2"},
+			},
+		},
+		{
+			name: "update with object-form assignees including confidence",
+			mockedRESTClient: func() *http.Client {
+				callCount := 0
+				return MockHTTPClientWithHandlers(map[string]http.HandlerFunc{
+					PatchReposIssuesByOwnerByRepoByIssueNumber: func(w http.ResponseWriter, r *http.Request) {
+						callCount++
+						var body map[string]any
+						require.NoError(t, json.NewDecoder(r.Body).Decode(&body))
+						if callCount == 2 {
+							assignees, ok := body["assignees"].([]any)
+							require.True(t, ok)
+							require.Len(t, assignees, 1)
+							a0, ok := assignees[0].(map[string]any)
+							require.True(t, ok)
+							assert.Equal(t, "octocat", a0["login"])
+							assert.Equal(t, "HIGH", a0["confidence"])
+							assert.Equal(t, "Expert in this area", a0["rationale"])
+						}
+						w.WriteHeader(http.StatusOK)
+						respBytes, _ := json.Marshal(mockIssue)
+						_, _ = w.Write(respBytes)
+					},
+				})
+			}(),
+			requestArgs: map[string]any{
+				"method":       "update",
+				"owner":        "owner",
+				"repo":         "repo",
+				"issue_number": float64(42),
+				"assignees": []any{
+					map[string]any{
+						"login":      "octocat",
+						"rationale":  "Expert in this area",
+						"confidence": "HIGH",
+					},
+				},
+			},
+		},
+		{
+			name:             "object-form assignee without login field fails",
+			mockedRESTClient: MockHTTPClientWithHandlers(map[string]http.HandlerFunc{}),
+			requestArgs: map[string]any{
+				"method":       "update",
+				"owner":        "owner",
+				"repo":         "repo",
+				"issue_number": float64(42),
+				"assignees": []any{
+					map[string]any{
+						"rationale": "Missing login",
+					},
+				},
+			},
+			expectError:    true,
+			expectedErrMsg: "each assignee object must have a 'login' string",
+		},
+		{
+			name:             "object-form assignee with invalid confidence fails",
+			mockedRESTClient: MockHTTPClientWithHandlers(map[string]http.HandlerFunc{}),
+			requestArgs: map[string]any{
+				"method":       "update",
+				"owner":        "owner",
+				"repo":         "repo",
+				"issue_number": float64(42),
+				"assignees": []any{
+					map[string]any{
+						"login":      "octocat",
+						"confidence": "VERY_HIGH",
+					},
+				},
+			},
+			expectError:    true,
+			expectedErrMsg: "confidence must be one of: LOW, MEDIUM, HIGH",
+		},
+		{
+			name:             "object-form assignee with rationale exceeding 280 chars fails",
+			mockedRESTClient: MockHTTPClientWithHandlers(map[string]http.HandlerFunc{}),
+			requestArgs: map[string]any{
+				"method":       "update",
+				"owner":        "owner",
+				"repo":         "repo",
+				"issue_number": float64(42),
+				"assignees": []any{
+					map[string]any{
+						"login":     "octocat",
+						"rationale": strings.Repeat("a", 281),
+					},
+				},
+			},
+			expectError:    true,
+			expectedErrMsg: "assignee rationale must be 280 characters or less",
+		},
+		{
+			name: "object-form assignee with only login falls back to string form",
+			mockedRESTClient: MockHTTPClientWithHandlers(map[string]http.HandlerFunc{
+				PatchReposIssuesByOwnerByRepoByIssueNumber: expectRequestBody(t, map[string]any{
+					"assignees": []any{"octocat"},
+				}).andThen(
+					mockResponse(t, http.StatusOK, mockIssue),
+				),
+			}),
+			requestArgs: map[string]any{
+				"method":       "update",
+				"owner":        "owner",
+				"repo":         "repo",
+				"issue_number": float64(42),
+				"assignees": []any{
+					map[string]any{
+						"login": "octocat",
+					},
+				},
+			},
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			restClient := mustNewGHClient(t, tc.mockedRESTClient)
+			gqlClient := githubv4.NewClient(githubv4mock.NewMockedHTTPClient())
+			deps := BaseDeps{
+				Client:         restClient,
+				GQLClient:      gqlClient,
+				featureChecker: featureCheckerFor(FeatureFlagIssueFields),
+			}
+			handler := serverTool.Handler(deps)
+
+			request := createMCPRequest(tc.requestArgs)
+			result, err := handler(ContextWithDeps(context.Background(), deps), &request)
+
+			if tc.expectError || tc.expectedErrMsg != "" {
+				require.NoError(t, err)
+				require.True(t, result.IsError)
+				errorContent := getErrorResult(t, result)
+				if tc.expectedErrMsg != "" {
+					assert.Contains(t, errorContent.Text, tc.expectedErrMsg)
+				}
+				return
+			}
+
+			require.NoError(t, err)
+			if result.IsError {
+				t.Fatalf("Unexpected error result: %s", getErrorResult(t, result).Text)
+			}
+			require.False(t, result.IsError)
+
+			textContent := getTextResult(t, result)
+			var resp MinimalResponse
+			require.NoError(t, json.Unmarshal([]byte(textContent.Text), &resp))
+			assert.Equal(t, "https://github.com/owner/repo/issues/42", resp.URL)
+		})
+	}
+}
+
 func Test_ParseISOTimestamp(t *testing.T) {
 	tests := []struct {
 		name         string