Cursor custom mode with a pinned skill: install the Sume skill
Cursor lets any skill be a custom mode pinned in the chat. Install the Sume skill with sume skills install; the mode cannot waive idempotency_key or MCP scope.
Cursor's changelog says any skill can be used as a Custom Mode, a skill that stays pinned in the chat. To pin Sume's, run sume skills install, which writes into .agents/skills or .claude/skills. The mode keeps the skill in view; it does not waive Sume's idempotency_key or scope checks.
Cursor's wording is from its changelog; the install and gate facts from Agent skills and MCP tools and gates, read 2026-10-01.
What is a Cursor custom mode?
Per the changelog (2026-08-19): "a skill that stays pinned in the chat", meant to keep agents focused on one skill, like an always-on skill. I did not find a setup path for choosing the folder in that page, so confirm in Cursor which skill folders it scans.
How do I get the Sume skill onto disk?
The CLI docs list these commands for the packaged skill.
| Command | Purpose |
|---|---|
sume skills list | Show bundled skills |
sume skills install | Write into .agents/skills or .claude/skills |
sume skills update | Refresh the installed skill |
sume skills export sume | Review the source files before a custom install |
sume skills remove sume | Remove it |
What can a pinned skill not waive?
The tools the skill calls come from hosted MCP at https://mcp.sume.com/mcp, and the gates live there: idempotency_key is required on write and paid tools, and there is no mcp:paid scope, so mutating tools need mcp:write or an API key. Pinning text in a chat changes what the agent is told, not what the server accepts. See skills and allowed tools.
How do I verify it works in the mode?
Start a chat in the mode and ask the agent to call tools_list. Then try a write or paid tool: a read-only OAuth session (mcp:read) returns insufficient_scope, so grant write at consent or use an API-key session.
Sources
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Written by Sume