E2E: Update addon-mcp tests to match new tool name.

[JReinhold]

To match changes in storybookjs/mcp#134

What I did

Checklist for Contributors

Testing

The changes in this PR are covered in the following automated tests:

• stories
• unit tests
• integration tests
• end-to-end tests

Manual testing

Caution

This section is mandatory for all contributions. If you believe no manual test is necessary, please state so explicitly. Thanks!

Documentation

• Add or update documentation reflecting your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Checklist for Maintainers

• When this PR is ready for testing, make sure to add ci:normal, ci:merged or ci:daily GH label to it to run a specific set of sandboxes. The particular set of sandboxes can be found in code/lib/cli-storybook/src/sandbox-templates.ts

• Make sure this PR contains one of the labels below:

  Available labels

  • bug: Internal changes that fixes incorrect behavior.
  • maintenance: User-facing maintenance tasks.
  • dependencies: Upgrading (sometimes downgrading) dependencies.
  • build: Internal-facing build tooling & test updates. Will not show up in release changelog.
  • cleanup: Minor cleanup style change. Will not show up in release changelog.
  • documentation: Documentation only changes. Will not show up in release changelog.
  • feature request: Introducing a new feature.
  • BREAKING CHANGE: Changes that break compatibility in some way with current major version.
  • other: Changes that don't fit in the above categories.

🦋 Canary release

This PR does not have a canary release associated. You can request a canary release of this pull request by mentioning the @storybookjs/core team here.

core team members can create a canary release here or locally with gh workflow run --repo storybookjs/storybook publish.yml --field pr=<PR_NUMBER>

Summary by CodeRabbit

• Tests
  • Updated end-to-end tests for the preview-stories tool to validate structured response formatting with preview URLs and story metadata.

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[github-actions]

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[coderabbitai]

📝 Walkthrough

Walkthrough

Updated e2e test for MCP preview-stories tool, introducing sandbox directory configuration from environment variable. Renamed test suite, modified MCP call arguments to include exportName and absoluteStoryPath, and refactored expected response structure to include structured metadata.

Changes

Cohort / File(s)	Summary
E2E MCP Tool Test code/e2e-tests/addon-mcp.spec.ts	Test suite renamed from "Tool: get-story-urls" to "Tool: preview-stories"; MCP call updated to use new tool name and argument structure (exportName, absoluteStoryPath); expected response refactored to validate structured content with story metadata instead of content-only assertions

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• E2E: Fix MCP tests also running in Preact sandboxes #33545: Modifies the same test file to adjust sandbox skip condition, working alongside these MCP call/response changes
• Manifests and MCP: Add e2e tests #33514: Directly related—also updates addon-mcp.spec.ts with changes to the story-URL tool renaming and response structure assertions for MCP preview-stories functionality

✨ Finishing touches

• 📝 Generate docstrings

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