Nothing to try yetTier: how much it should matter to you
2Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
PluginsArea: what it touches
ImprovementsKind: in v2.1.283,
ImprovementsSection of the release
What
MCP servers are outside programs that give Claude extra tools. Some need you to sign in with OAuth, a standard login flow, and for that the terminal must register itself with the server as a client.
Remembering the answer: when sign-in discovery finds that a server has no registration_endpoint and does not support client ID metadata documents, Claude Code now records the time as registrationNotOfferedAt in its credentials store. This recording happens without any flag.
Leaving servers out: for plugins synced from claude.ai, each HTTP or SSE MCP server with no clientId, no xaa setting and no credentials in its URL is checked against that record. If the record is less than 30 days old, the server is removed from the plugin and the debug log notes "Left out MCP server". This only happens when the flag tengu_starry_locket is on; its built-in default is false.
Checking again: if the record is older than 30 days, or dated in the future, the server is marked redialToRelearnRegistration instead. It is connected again and sign-in discovery runs fresh.
Skipping discovery: a second flag, tengu_twinkly_prism, skips MCP server discovery for claude.ai-synced plugins entirely.
Nothing has been read about tengu_starry_locket or tengu_twinkly_prism from the flag server.
Why
MCP servers from synced plugins that can never finish signing in from a terminal would stop showing up as failed sign-ins in /mcp. The 30-day window means such a server is checked again later in case it starts allowing registration.
Read from
Feature flag
tengu_starry_locketOff in both readings
The flag server returned off for the account this site reads and for the anonymous baseline. A reading of off cannot rule out a rollout these two readings sit outside of.
This account: off · anonymous baseline: off · compiled default in v2.1.283: off
These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.
Flag reading movedThe flag server now returns off for tengu_starry_locket, read as this account.A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.
Flag reading movedThe flag server now returns nothing at all, having stopped carrying it for tengu_starry_locket, read as this account.A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtExactly which plugin sources count as synced for this check is not settled.
Anthropic's release notes agreeFixed MCP sign-in for a server with no valid URL failing with an opaque SDK error; /mcp no longer offers Authenticate for such servers
The name it cites is new in this buildNew in this build: tengu_starry_locket
