Atlassian MCP: Add support for downloading Jira attachment content

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

The Atlassian MCP connector can retrieve Jira issue data including attachment metadata (filename, size, content URL), but cannot download the attachment content itself. The fetch tool only accepts Atlassian Resource Identifiers (ARIs) — it does not accept the raw https://api.atlassian.com/.../attachment/content/... URLs returned in issue data.
This affects both Claude Cowork (desktop) and Claude Code (CLI) users — anyone using the Atlassian MCP connector hits this gap regardless of how they connect.

Proposed Solution

Extend the Atlassian MCP connector to support downloading attachment content, either by:

Accepting attachment content URLs in the fetch tool (handling the Atlassian auth transparently), or
Adding a dedicated get_attachment_content tool that takes an attachment ID or content URL and returns the file

Alternative Solutions

Current workaround: the assistant lists attachment filenames and Jira content URLs in a markdown file, and the user downloads them manually from the browser. This is functional but breaks the assistant's ability to read logs, analyse screenshots, or work with documents attached to tickets.

Priority

Medium - Would be very helpful

Feature Category

MCP server integration

Use Case Example

When building a project seed file from a Jira ticket (e.g. a bug with a stack trace screenshot or attached log file), the assistant can list the attachments but cannot read them. The user has to download each file manually, then re-upload or paste the contents. In a triage workflow where the key evidence is in an attachment, this requires an extra manual round-trip every time.

Additional Context

Related closed issue: #18359 — closed as a duplicate, but the duplicate chain appears to have no surviving open issue. If there is a canonical open issue, this could be a comment/upvote instead.
Affects both Claude Cowork and Claude Code CLI users equally — the limitation is in the shared MCP connector, not surface-specific.