fix(tools): Support unassigning issues (#1302)

Treat an explicit null assignee as a request to clear assignment while
preserving omission as no update. This is similar to how the monitor
update tool works.

Co-authored-by: Codex CLI Agent <noreply@openai.com>

Author: cvxluo

packages/mcp-core/src/api-client/client.ts

@@ -4109,7 +4109,7 @@ export class SentryApiService {
       organizationSlug: string;
       issueId: string;
       status?: string;
-      assignedTo?: string;
+      assignedTo?: string | null;
       substatus?: string;
       ignoreDuration?: number;
       ignoreCount?: number;
@@ -4130,7 +4130,7 @@ export class SentryApiService {
       ignoreUserWindow?: number;
     } = {};
     if (status !== undefined) updateData.status = status;
-    if (assignedTo !== undefined) updateData.assignedTo = assignedTo;
+    if (assignedTo !== undefined) updateData.assignedTo = assignedTo ?? "";
     if (substatus !== undefined) updateData.substatus = substatus;
     if (ignoreDuration !== undefined)
       updateData.ignoreDuration = ignoreDuration;

packages/mcp-core/src/schema.ts

@@ -177,8 +177,10 @@ export const ParamIssueIgnoreMode = z
 export const ParamAssignedTo = z
   .string()
   .trim()
+  .min(1)
+  .nullable()
   .describe(
-    "The assignee in format 'user:ID' or 'team:ID_OR_SLUG' where ID is numeric. Example: 'user:123456', 'team:789', or 'team:my-team-slug'. Use `execute_sentry_tool(name='whoami', arguments={})` to find your user ID.",
+    "The assignee in format 'user:ID' or 'team:ID_OR_SLUG' where ID is numeric. Pass null to unassign the issue. Example: 'user:123456', 'team:789', or 'team:my-team-slug'. Use `execute_sentry_tool(name='whoami', arguments={})` to find your user ID.",
   );
 
 export const ParamIgnoreDurationMinutes = z

packages/mcp-core/src/skillDefinitions.json

@@ -400,7 +400,7 @@
       },
       {
         "name": "update_issue",
-        "description": "Update a Sentry issue's status or assignment.\n\nUse this to resolve, reopen, assign, or ignore an issue.\n\n<examples>\n```\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', status='resolved')\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', assignedTo='user:123456')\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', status='ignored')\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', status='ignored', ignoreMode='forever')\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', status='ignored', ignoreMode='untilOccurrenceCount', ignoreCount=100, ignoreWindowMinutes=60)\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', status='ignored', reason='Ignoring because this is expected noise from the staging deploy')\n```\n</examples>\n\n<hints>\n- Provide `issueUrl` or `organizationSlug` + `issueId`.\n- At least one of `status` or `assignedTo` is required.\n- `assignedTo` format: `user:ID` or `team:ID_OR_SLUG`.\n- Use `execute_sentry_tool(name='whoami', arguments={})` to find your user ID for self-assignment.\n- Status values: `resolved`, `resolvedInNextRelease`, `unresolved`, `ignored`.\n- `status='ignored'` defaults to `ignoreMode='untilEscalating'`.\n- Ignore modes: `untilEscalating`, `forever`, `forDuration`, `untilOccurrenceCount`, `untilUserCount`.\n- Matching ignore inputs are `ignoreDurationMinutes`, `ignoreCount` + optional `ignoreWindowMinutes`, or `ignoreUserCount` + optional `ignoreUserWindowMinutes`.\n- To switch an already ignored issue between `untilEscalating`, `forever`, and condition-based ignore modes, first set `status='unresolved'`, then ignore it again with the new rule.\n- `reason` is optional. When provided, it will be posted as a comment on the issue's activity feed explaining why the action was taken.\n</hints>",
+        "description": "Update a Sentry issue's status or assignment.\n\nUse this to resolve, reopen, assign, unassign, or ignore an issue.\n\n<examples>\n```\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', status='resolved')\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', assignedTo='user:123456')\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', assignedTo=null)\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', status='ignored')\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', status='ignored', ignoreMode='forever')\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', status='ignored', ignoreMode='untilOccurrenceCount', ignoreCount=100, ignoreWindowMinutes=60)\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', status='ignored', reason='Ignoring because this is expected noise from the staging deploy')\n```\n</examples>\n\n<hints>\n- Provide `issueUrl` or `organizationSlug` + `issueId`.\n- At least one of `status` or `assignedTo` is required.\n- Omit `assignedTo` to leave assignment unchanged. Pass `null` to unassign; otherwise use `user:ID` or `team:ID_OR_SLUG`.\n- Use `execute_sentry_tool(name='whoami', arguments={})` to find your user ID for self-assignment.\n- Status values: `resolved`, `resolvedInNextRelease`, `unresolved`, `ignored`.\n- `status='ignored'` defaults to `ignoreMode='untilEscalating'`.\n- Ignore modes: `untilEscalating`, `forever`, `forDuration`, `untilOccurrenceCount`, `untilUserCount`.\n- Matching ignore inputs are `ignoreDurationMinutes`, `ignoreCount` + optional `ignoreWindowMinutes`, or `ignoreUserCount` + optional `ignoreUserWindowMinutes`.\n- To switch an already ignored issue between `untilEscalating`, `forever`, and condition-based ignore modes, first set `status='unresolved'`, then ignore it again with the new rule.\n- `reason` is optional. When provided, it will be posted as a comment on the issue's activity feed explaining why the action was taken.\n</hints>",
         "requiredScopes": ["event:write"]
       },
       {

packages/mcp-core/src/toolDefinitions.json

@@ -5659,7 +5659,7 @@
   },
   {
     "name": "update_issue",
-    "description": "Update a Sentry issue's status or assignment.\n\nUse this to resolve, reopen, assign, or ignore an issue.\n\n<examples>\n```\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', status='resolved')\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', assignedTo='user:123456')\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', status='ignored')\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', status='ignored', ignoreMode='forever')\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', status='ignored', ignoreMode='untilOccurrenceCount', ignoreCount=100, ignoreWindowMinutes=60)\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', status='ignored', reason='Ignoring because this is expected noise from the staging deploy')\n```\n</examples>\n\n<hints>\n- Provide `issueUrl` or `organizationSlug` + `issueId`.\n- At least one of `status` or `assignedTo` is required.\n- `assignedTo` format: `user:ID` or `team:ID_OR_SLUG`.\n- Use `execute_sentry_tool(name='whoami', arguments={})` to find your user ID for self-assignment.\n- Status values: `resolved`, `resolvedInNextRelease`, `unresolved`, `ignored`.\n- `status='ignored'` defaults to `ignoreMode='untilEscalating'`.\n- Ignore modes: `untilEscalating`, `forever`, `forDuration`, `untilOccurrenceCount`, `untilUserCount`.\n- Matching ignore inputs are `ignoreDurationMinutes`, `ignoreCount` + optional `ignoreWindowMinutes`, or `ignoreUserCount` + optional `ignoreUserWindowMinutes`.\n- To switch an already ignored issue between `untilEscalating`, `forever`, and condition-based ignore modes, first set `status='unresolved'`, then ignore it again with the new rule.\n- `reason` is optional. When provided, it will be posted as a comment on the issue's activity feed explaining why the action was taken.\n</hints>",
+    "description": "Update a Sentry issue's status or assignment.\n\nUse this to resolve, reopen, assign, unassign, or ignore an issue.\n\n<examples>\n```\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', status='resolved')\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', assignedTo='user:123456')\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', assignedTo=null)\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', status='ignored')\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', status='ignored', ignoreMode='forever')\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', status='ignored', ignoreMode='untilOccurrenceCount', ignoreCount=100, ignoreWindowMinutes=60)\nupdate_issue(organizationSlug='my-org', issueId='PROJECT-123', status='ignored', reason='Ignoring because this is expected noise from the staging deploy')\n```\n</examples>\n\n<hints>\n- Provide `issueUrl` or `organizationSlug` + `issueId`.\n- At least one of `status` or `assignedTo` is required.\n- Omit `assignedTo` to leave assignment unchanged. Pass `null` to unassign; otherwise use `user:ID` or `team:ID_OR_SLUG`.\n- Use `execute_sentry_tool(name='whoami', arguments={})` to find your user ID for self-assignment.\n- Status values: `resolved`, `resolvedInNextRelease`, `unresolved`, `ignored`.\n- `status='ignored'` defaults to `ignoreMode='untilEscalating'`.\n- Ignore modes: `untilEscalating`, `forever`, `forDuration`, `untilOccurrenceCount`, `untilUserCount`.\n- Matching ignore inputs are `ignoreDurationMinutes`, `ignoreCount` + optional `ignoreWindowMinutes`, or `ignoreUserCount` + optional `ignoreUserWindowMinutes`.\n- To switch an already ignored issue between `untilEscalating`, `forever`, and condition-based ignore modes, first set `status='unresolved'`, then ignore it again with the new rule.\n- `reason` is optional. When provided, it will be posted as a comment on the issue's activity feed explaining why the action was taken.\n</hints>",
     "inputSchema": {
       "type": "object",
       "properties": {
@@ -5699,8 +5699,16 @@
           "description": "The new status for the issue. Valid values are 'resolved', 'resolvedInNextRelease', 'unresolved', and 'ignored'."
         },
         "assignedTo": {
-          "type": "string",
-          "description": "The assignee in format 'user:ID' or 'team:ID_OR_SLUG' where ID is numeric. Example: 'user:123456', 'team:789', or 'team:my-team-slug'. Use `execute_sentry_tool(name='whoami', arguments={})` to find your user ID."
+          "anyOf": [
+            {
+              "type": "string",
+              "minLength": 1
+            },
+            {
+              "type": "null"
+            }
+          ],
+          "description": "The assignee in format 'user:ID' or 'team:ID_OR_SLUG' where ID is numeric. Pass null to unassign the issue. Example: 'user:123456', 'team:789', or 'team:my-team-slug'. Use `execute_sentry_tool(name='whoami', arguments={})` to find your user ID."
         },
         "ignoreMode": {
           "type": "string",

packages/mcp-core/src/tools/catalog/update-issue.test.ts

@@ -96,6 +96,44 @@ describe("update_issue", () => {
     `);
   });
 
+  it("unassigns an issue", async () => {
+    let requestBody: Record<string, unknown> | undefined;
+    const currentIssue = createIssue();
+    const updatedIssue = createIssue({ assignedTo: null });
+
+    mswServer.use(
+      http.get(
+        "https://sentry.io/api/0/organizations/sentry-mcp-evals/issues/CLOUDFLARE-MCP-41/",
+        () => HttpResponse.json(currentIssue),
+      ),
+      http.put(
+        "https://sentry.io/api/0/organizations/sentry-mcp-evals/issues/CLOUDFLARE-MCP-41/",
+        async ({ request }) => {
+          requestBody = (await request.json()) as Record<string, unknown>;
+          return HttpResponse.json(updatedIssue);
+        },
+      ),
+    );
+
+    const result = await updateIssue.handler(
+      {
+        organizationSlug: "sentry-mcp-evals",
+        issueId: "CLOUDFLARE-MCP-41",
+        status: undefined,
+        assignedTo: null,
+        issueUrl: undefined,
+        regionUrl: null,
+      },
+      serverContext,
+    );
+
+    expect(requestBody).toEqual({ assignedTo: "" });
+    expect(result).toContain(
+      "**Assigned To**: Jane Developer → **Unassigned**",
+    );
+    expect(result).toContain("**Assigned To**: Unassigned");
+  });
+
   it("skips status updates when the requested status is already set", async () => {
     let putCalled = false;
     const currentIssue = createIssue({

packages/mcp-core/src/tools/catalog/update-issue.ts

@@ -339,10 +339,18 @@ function buildNoChangesOutput(params: {
 
 function isAssigneeAlreadySet(
   issue: Issue,
-  requestedAssignee: string | undefined,
+  requestedAssignee: string | null | undefined,
   currentUserId: string | null | undefined,
 ): boolean {
-  if (!requestedAssignee || !issue.assignedTo) {
+  if (requestedAssignee === undefined) {
+    return false;
+  }
+
+  if (requestedAssignee === null) {
+    return !issue.assignedTo;
+  }
+
+  if (!issue.assignedTo) {
     return false;
   }
 
@@ -622,12 +630,13 @@ export default defineTool({
   description: [
     "Update a Sentry issue's status or assignment.",
     "",
-    "Use this to resolve, reopen, assign, or ignore an issue.",
+    "Use this to resolve, reopen, assign, unassign, or ignore an issue.",
     "",
     "<examples>",
     "```",
     "update_issue(organizationSlug='my-org', issueId='PROJECT-123', status='resolved')",
     "update_issue(organizationSlug='my-org', issueId='PROJECT-123', assignedTo='user:123456')",
+    "update_issue(organizationSlug='my-org', issueId='PROJECT-123', assignedTo=null)",
     "update_issue(organizationSlug='my-org', issueId='PROJECT-123', status='ignored')",
     "update_issue(organizationSlug='my-org', issueId='PROJECT-123', status='ignored', ignoreMode='forever')",
     "update_issue(organizationSlug='my-org', issueId='PROJECT-123', status='ignored', ignoreMode='untilOccurrenceCount', ignoreCount=100, ignoreWindowMinutes=60)",
@@ -638,7 +647,7 @@ export default defineTool({
     "<hints>",
     "- Provide `issueUrl` or `organizationSlug` + `issueId`.",
     "- At least one of `status` or `assignedTo` is required.",
-    "- `assignedTo` format: `user:ID` or `team:ID_OR_SLUG`.",
+    "- Omit `assignedTo` to leave assignment unchanged. Pass `null` to unassign; otherwise use `user:ID` or `team:ID_OR_SLUG`.",
     "- Use `execute_sentry_tool(name='whoami', arguments={})` to find your user ID for self-assignment.",
     "- Status values: `resolved`, `resolvedInNextRelease`, `unresolved`, `ignored`.",
     "- `status='ignored'` defaults to `ignoreMode='untilEscalating'`.",
@@ -688,7 +697,7 @@ export default defineTool({
     }
 
     // Validate that at least one update parameter is provided
-    if (!params.status && !params.assignedTo) {
+    if (params.status === undefined && params.assignedTo === undefined) {
       throw new UserInputError(
         "At least one of `status` or `assignedTo` must be provided to update the issue",
       );
@@ -762,7 +771,11 @@ export default defineTool({
       currentIssue.shortId,
     );
 
-    if (!updateStatus && !updateAssignedTo && !updateIgnore) {
+    if (
+      updateStatus === undefined &&
+      updateAssignedTo === undefined &&
+      updateIgnore === undefined
+    ) {
       const commentResult = await tryPostReasonComment(
         apiService,
         orgSlug,
@@ -834,7 +847,7 @@ export default defineTool({
       }
     }
 
-    if (updateAssignedTo && assignmentChanged) {
+    if (updateAssignedTo !== undefined && assignmentChanged) {
       const oldAssignee = formatAssignedTo(currentIssue.assignedTo ?? null);
       const newAssignee =
         params.assignedTo === "me"