attach_file — MCP tool

added 2026-09-29

Upload a file to an issue (needs edit access). Send the file's bytes base64-encoded, at most 3000000 bytes decoded. The result gives a Markdown snippet: put it into the description (update_description) to show an image inline. Images (PNG, JPEG, GIF, WebP) display inline, other files download.

content_base64stringrequired
File content, standard base64
content_typestringoptional
MIME type (optional; derived from the file name)
filenamestringrequired
File name including extension, e.g. mockup.png
keystringrequired
Issue key

Returns

contentTypestringrequired
filenamestringrequired
idstring (uuid)required
issuestringrequired
Issue key
markdownstringrequired
Snippet for update_description (an image shows inline)
sizeintegerrequired
Bytes
urlstringrequired

2026-10-04 — The storage quota is the project owner's plan storage (get_preferences shows it); a full one refuses with code upload_quota_exceeded and details {limit: storage_bytes, used, max, plan, subject} in bytes (used and max only when the storage is yours; files in archived projects count too).
2026-10-03 — Also answers structuredContent (see outputSchema); a failed call adds structuredContent.error. Text unchanged. Details: /docs/mcp, "Structured results and errors".
2026-10-04 — Claude Code 2.1.288+ (clientInfo claude-code): the text of a successful answer is itself up to 512 bytes, else "Result in structuredContent (N bytes)."; structuredContent and errors are unchanged. See /docs/mcp.