diff --git a/.github/workflows/issue-triage.yml b/.github/workflows/issue-triage.yml
index 4eb7fd5..7d821a2 100644
--- a/.github/workflows/issue-triage.yml
+++ b/.github/workflows/issue-triage.yml
@@ -32,7 +32,7 @@ jobs:
                   "--rm",
                   "-e",
                   "GITHUB_PERSONAL_ACCESS_TOKEN",
-                  "ghcr.io/github/github-mcp-server:sha-7aced2b"
+                  "ghcr.io/github/github-mcp-server:sha-6d69797"
                 ],
                 "env": {
                   "GITHUB_PERSONAL_ACCESS_TOKEN": "${{ secrets.GITHUB_TOKEN }}"
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 96824d1..74e6140 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -50,20 +50,6 @@ Thank you for your interest in contributing to Claude Code Action! This document
    bun test
    ```
 
-2. **Integration Tests** (using GitHub Actions locally):
-
-   ```bash
-   ./test-local.sh
-   ```
-
-   This script:
-
-   - Installs `act` if not present (requires Homebrew on macOS)
-   - Runs the GitHub Action workflow locally using Docker
-   - Requires your `ANTHROPIC_API_KEY` to be set
-
-   On Apple Silicon Macs, the script automatically adds the `--container-architecture linux/amd64` flag to avoid compatibility issues.
-
 ## Pull Request Process
 
 1. Create a new branch from `main`:
@@ -103,13 +89,7 @@ Thank you for your interest in contributing to Claude Code Action! This document
 
 When modifying the action:
 
-1. Test locally with the test script:
-
-   ```bash
-   ./test-local.sh
-   ```
-
-2. Test in a real GitHub Actions workflow by:
+1. Test in a real GitHub Actions workflow by:
    - Creating a test repository
    - Using your branch as the action source:
      ```yaml
diff --git a/action.yml b/action.yml
index 8f489f7..081decc 100644
--- a/action.yml
+++ b/action.yml
@@ -114,7 +114,7 @@ runs:
     - name: Run Claude Code
       id: claude-code
       if: steps.prepare.outputs.contains_trigger == 'true'
-      uses: anthropics/claude-code-base-action@f481f924b73a7085d9efea0e50a3ba171ed1d74b # v0.0.20
+      uses: anthropics/claude-code-base-action@ce5cfd683932f58cb459e749f20b06d2fb30c265 # v0.0.25
       with:
         prompt_file: ${{ runner.temp }}/claude-prompts/claude-prompt.txt
         allowed_tools: ${{ env.ALLOWED_TOOLS }}
diff --git a/src/create-prompt/index.ts b/src/create-prompt/index.ts
index 876c5d6..7e1c9d6 100644
--- a/src/create-prompt/index.ts
+++ b/src/create-prompt/index.ts
@@ -243,7 +243,7 @@ export function prepareContext(
       }
 
       if (eventAction === "assigned") {
-        if (!assigneeTrigger) {
+        if (!assigneeTrigger && !directPrompt) {
           throw new Error(
             "ASSIGNEE_TRIGGER is required for issue assigned event",
           );
@@ -255,7 +255,7 @@ export function prepareContext(
           issueNumber,
           baseBranch,
           claudeBranch,
-          assigneeTrigger,
+          ...(assigneeTrigger && { assigneeTrigger }),
         };
       } else if (eventAction === "labeled") {
         if (!labelTrigger) {
@@ -350,7 +350,9 @@ export function getEventTypeAndContext(envVars: PreparedContext): {
       }
       return {
         eventType: "ISSUE_ASSIGNED",
-        triggerContext: `issue assigned to '${eventData.assigneeTrigger}'`,
+        triggerContext: eventData.assigneeTrigger
+          ? `issue assigned to '${eventData.assigneeTrigger}'`
+          : `issue assigned event`,
       };
 
     case "pull_request":
diff --git a/src/create-prompt/types.ts b/src/create-prompt/types.ts
index 618b33d..218eb65 100644
--- a/src/create-prompt/types.ts
+++ b/src/create-prompt/types.ts
@@ -65,7 +65,7 @@ type IssueAssignedEvent = {
   issueNumber: string;
   baseBranch: string;
   claudeBranch: string;
-  assigneeTrigger: string;
+  assigneeTrigger?: string;
 };
 
 type IssueLabeledEvent = {
diff --git a/src/github/context.ts b/src/github/context.ts
index 214f2ca..2e92e89 100644
--- a/src/github/context.ts
+++ b/src/github/context.ts
@@ -1,6 +1,7 @@
 import * as github from "@actions/github";
 import type {
   IssuesEvent,
+  IssuesAssignedEvent,
   IssueCommentEvent,
   PullRequestEvent,
   PullRequestReviewEvent,
@@ -149,3 +150,9 @@ export function isPullRequestReviewCommentEvent(
 ): context is ParsedGitHubContext & { payload: PullRequestReviewCommentEvent } {
   return context.eventName === "pull_request_review_comment";
 }
+
+export function isIssuesAssignedEvent(
+  context: ParsedGitHubContext,
+): context is ParsedGitHubContext & { payload: IssuesAssignedEvent } {
+  return isIssuesEvent(context) && context.eventAction === "assigned";
+}
diff --git a/src/github/validation/trigger.ts b/src/github/validation/trigger.ts
index 333f617..edb2c21 100644
--- a/src/github/validation/trigger.ts
+++ b/src/github/validation/trigger.ts
@@ -3,6 +3,7 @@
 import * as core from "@actions/core";
 import {
   isIssuesEvent,
+  isIssuesAssignedEvent,
   isIssueCommentEvent,
   isPullRequestEvent,
   isPullRequestReviewEvent,
@@ -22,10 +23,10 @@ export function checkContainsTrigger(context: ParsedGitHubContext): boolean {
   }
 
   // Check for assignee trigger
-  if (isIssuesEvent(context) && context.eventAction === "assigned") {
+  if (isIssuesAssignedEvent(context)) {
     // Remove @ symbol from assignee_trigger if present
     let triggerUser = assigneeTrigger.replace(/^@/, "");
-    const assigneeUsername = context.payload.issue.assignee?.login || "";
+    const assigneeUsername = context.payload.assignee?.login || "";
 
     if (triggerUser && assigneeUsername === triggerUser) {
       console.log(`Issue assigned to trigger user '${triggerUser}'`);
diff --git a/src/mcp/install-mcp-server.ts b/src/mcp/install-mcp-server.ts
index 0fa5436..8748f67 100644
--- a/src/mcp/install-mcp-server.ts
+++ b/src/mcp/install-mcp-server.ts
@@ -62,7 +62,7 @@ export async function prepareMcpConfig(
           "--rm",
           "-e",
           "GITHUB_PERSONAL_ACCESS_TOKEN",
-          "ghcr.io/github/github-mcp-server:sha-e9f748f", // https://github.com/github/github-mcp-server/releases/tag/v0.4.0
+          "ghcr.io/github/github-mcp-server:sha-6d69797", // https://github.com/github/github-mcp-server/releases/tag/v0.5.0
         ],
         env: {
           GITHUB_PERSONAL_ACCESS_TOKEN: githubToken,
diff --git a/test/create-prompt.test.ts b/test/create-prompt.test.ts
index 7ae1ff7..df10668 100644
--- a/test/create-prompt.test.ts
+++ b/test/create-prompt.test.ts
@@ -663,6 +663,29 @@ describe("getEventTypeAndContext", () => {
     expect(result.eventType).toBe("ISSUE_LABELED");
     expect(result.triggerContext).toBe("issue labeled with 'claude-task'");
   });
+
+  test("should return correct type and context for issue assigned without assigneeTrigger", () => {
+    const envVars: PreparedContext = {
+      repository: "owner/repo",
+      claudeCommentId: "12345",
+      triggerPhrase: "@claude",
+      directPrompt: "Please assess this issue",
+      eventData: {
+        eventName: "issues",
+        eventAction: "assigned",
+        isPR: false,
+        issueNumber: "999",
+        baseBranch: "main",
+        claudeBranch: "claude/issue-999-20240101_120000",
+        // No assigneeTrigger when using directPrompt
+      },
+    };
+
+    const result = getEventTypeAndContext(envVars);
+
+    expect(result.eventType).toBe("ISSUE_ASSIGNED");
+    expect(result.triggerContext).toBe("issue assigned event");
+  });
 });
 
 describe("buildAllowedToolsString", () => {
diff --git a/test/mockContext.ts b/test/mockContext.ts
index a843ee9..c41146e 100644
--- a/test/mockContext.ts
+++ b/test/mockContext.ts
@@ -92,6 +92,12 @@ export const mockIssueAssignedContext: ParsedGitHubContext = {
   actor: "admin-user",
   payload: {
     action: "assigned",
+    assignee: {
+      login: "claude-bot",
+      id: 11111,
+      avatar_url: "https://avatars.githubusercontent.com/u/11111",
+      html_url: "https://github.com/claude-bot",
+    },
     issue: {
       number: 123,
       title: "Feature: Add dark mode support",
diff --git a/test/prepare-context.test.ts b/test/prepare-context.test.ts
index 7811c5b..904dd37 100644
--- a/test/prepare-context.test.ts
+++ b/test/prepare-context.test.ts
@@ -219,6 +219,55 @@ describe("parseEnvVarsWithContext", () => {
         ),
       ).toThrow("BASE_BRANCH is required for issues event");
     });
+
+    test("should allow issue assigned event with direct_prompt and no assigneeTrigger", () => {
+      const contextWithDirectPrompt = createMockContext({
+        ...mockIssueAssignedContext,
+        inputs: {
+          ...mockIssueAssignedContext.inputs,
+          assigneeTrigger: "", // No assignee trigger
+          directPrompt: "Please assess this issue", // But direct prompt is provided
+        },
+      });
+
+      const result = prepareContext(
+        contextWithDirectPrompt,
+        "12345",
+        "main",
+        "claude/issue-123-20240101_120000",
+      );
+
+      expect(result.eventData.eventName).toBe("issues");
+      expect(result.eventData.isPR).toBe(false);
+      expect(result.directPrompt).toBe("Please assess this issue");
+      if (
+        result.eventData.eventName === "issues" &&
+        result.eventData.eventAction === "assigned"
+      ) {
+        expect(result.eventData.issueNumber).toBe("123");
+        expect(result.eventData.assigneeTrigger).toBeUndefined();
+      }
+    });
+
+    test("should throw error when neither assigneeTrigger nor directPrompt provided for issue assigned event", () => {
+      const contextWithoutTriggers = createMockContext({
+        ...mockIssueAssignedContext,
+        inputs: {
+          ...mockIssueAssignedContext.inputs,
+          assigneeTrigger: "", // No assignee trigger
+          directPrompt: "", // No direct prompt
+        },
+      });
+
+      expect(() =>
+        prepareContext(
+          contextWithoutTriggers,
+          "12345",
+          "main",
+          "claude/issue-123-20240101_120000",
+        ),
+      ).toThrow("ASSIGNEE_TRIGGER is required for issue assigned event");
+    });
   });
 
   describe("optional fields", () => {
diff --git a/test/trigger-validation.test.ts b/test/trigger-validation.test.ts
index 8d8f23c..36708c0 100644
--- a/test/trigger-validation.test.ts
+++ b/test/trigger-validation.test.ts
@@ -90,6 +90,11 @@ describe("checkContainsTrigger", () => {
         ...mockIssueAssignedContext,
         payload: {
           ...mockIssueAssignedContext.payload,
+          assignee: {
+            ...(mockIssueAssignedContext.payload as IssuesAssignedEvent)
+              .assignee,
+            login: "otherUser",
+          },
           issue: {
             ...(mockIssueAssignedContext.payload as IssuesAssignedEvent).issue,
             assignee: {