added 2026-09-28can overwrite dataidempotent
Replace an issue's description with Markdown. Inline comment threads are re-attached to their quoted text when it still exists; otherwise they become outdated. base_rev (the description revision, the base_rev field of get_issue_details) is required: if the description changed since, nothing is written and the answer gives the current revision; re-read, merge your edit and send again with that revision. A retry of the same text converges (no conflict).
base_revintegerrequiredDescription revision you based the edit on: the base_rev field of get_issue_details. Required. If someone changed the description since, the update is rejected and the answer gives the current revision.keystringrequiredIssue keymarkdownstringrequiredFull new description in Markdown: edit the text between the description markers of get_issue_details (without the markers). "" clears the description.  = sysdraw view link; a ```mermaid block is drawn as a diagram
Returns
changedbooleanrequiredFalse when the text was the same: nothing was savedkeystringrequiredorphaned_threadsintegerrequiredInline comment threads that lost their text and moved to OutdatedversionintegerrequiredDescription version (get_description_version)
- 2026-10-03 — BREAKING: base_rev is now required. A call without it is rejected (base_rev_required) and nothing is written; the old implicit overwrite is gone. Migrate: read base_rev from get_issue_details, send it with the Markdown; on a conflict the answer gives the current revision: re-read, merge, send again with it. Sending the same text again converges.
- 2026-10-01 — Markdown round trip: the Markdown you send is read back the way get_issue_details shows it. In a blockquote a line holding only is an empty paragraph; marks nest in one fixed order; mention labels are escaped. Spaces at the edges of bold/italic move outside the mark and a hard break in a heading becomes a space.
- 2026-10-01 — An unchanged description is a no-op: the revision no longer moves.
- 2026-10-05 — Every tool now refuses an argument its input schema does not declare, or a missing required one (nothing is written), naming it and the closest declared name. Here markdown is required: send "" to clear.
- 2026-10-06 — A sysdraw diagram can be embedded in a description or comment: write its view link as an image line,  (a bare link stays a link); get_issue_details shows it the same way. Only view links anyone can open are accepted; a comment, edit or signed-in-only link is refused with the reason, and a new diagram is saved only after sysdraw confirmed it (a person can add about 60 new links per 15 minutes; when sysdraw cannot be asked the call fails and can be retried). Diagrams already in the text are not checked again.
- 2026-10-09 — A Mermaid diagram can be written in a description or comment as a fenced code block: ```mermaid, the diagram source, ```. The web app draws it as a diagram (with a Show source toggle); the source stays in the text and get_issue_details gives it back unchanged. Not drawn (the source is shown instead): config directives (%%{init: ...}%% lines), front matter (a leading --- block), image shapes (img:), and diagrams over about 20 000 characters or 500 lines; one over about 8 000 characters or 150 lines (a mindmap: 80 lines) is drawn when the reader presses Draw.
- 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.