tengu_sdk_mcp_manifests
A Claude Code feature flag, read out of the shipped bundle. It has been in the build since v2.1.265, including the newest one read.
SDK-registered in-process MCP servers can now skip a round-trip handshake at session start
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.265.
In the changelogs
3Releases whose published page names tengu_sdk_mcp_manifests.
-
v2.1.288
Remote session owner-only check reworked, with a remote cowork case added
The check for whether a remote session is limited to the owner's account is now shared, and a separate check for remote cowork sessions was added
gate cited by this entry
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v2.1.286
Remote sessions need extra conditions to use SDK MCP server manifests
Remote sessions use SDK MCP manifests only when owner-only and a separate server switch, off by default, allows it
gate cited by this entry
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v2.1.265
SDK MCP servers can now skip the control-channel handshake via manifests
SDK-registered in-process MCP servers can now skip a round-trip handshake at session start
gate cited by this entry
Gate readings
3| Release | Resolved | This account | Anonymous | Compiled default |
|---|---|---|---|---|
| v2.1.288 read on another version | On for this account, and not off by default | on | on | on |
| v2.1.286 read on another version | On for this account, and not off by default | on | on | on |
| v2.1.265 | Not enough to say | no value returned | no value returned | on |
Two arms, because they disagree: this account is the one account this site reads and anonymous is a baseline with no identity attached. A reading says nothing about your account, and off cannot rule out a rollout both readings sit outside of. What these readings can and cannot show.
Flag server, over time
6| Read as | Reading | From | Until | Version installed |
|---|---|---|---|---|
| anonymous | on | 2026-10-17T05:30:04Z | 2026-11-12T07:35:04Z | v2.1.302 to v2.1.322 |
| this account | on | 2026-09-14T21:40:04Z | 2026-11-12T07:35:04Z | v2.1.270 to v2.1.322 |
| anonymous | no longer carried | 2026-10-17T05:25:57Z | 2026-10-17T05:25:57Z | v2.1.302 |
| anonymous | on | 2026-09-14T20:36:35Z | 2026-10-17T05:10:04Z | v2.1.271 to v2.1.302 |
| this account | no longer carried | 2026-09-14T20:40:05Z | 2026-09-14T20:40:05Z | v2.1.270 |
| this account | on | 2026-09-14T20:36:35Z | 2026-09-14T20:36:35Z | v2.1.271 |
One row per unbroken stretch of one reading, newest first, from snapshots taken every twenty-five minutes or so. No longer carried is not off: it means the flag server stopped returning the gate at all, which is what a retired experiment looks like. The version column is what was installed when the reading was taken, not what caused it.
First cited
0No release's published evidence quotes this name. The ledger indexes the Evidence lines of every changelog on this site, so this says nobody here has ever quoted it; it says nothing about how old the name is.
Presence across releases
1Build by build
53One row per release since the first build this name was read out of. Absent means the build was read and the name was not in it, never mined means no bundle for that release was ever archived, and a declared type or a default is only ever what that release's own bundle stated.
Read out of the published npm bundle release by release, and out of Anthropic's own documentation as this site captured it. Nothing on this page is a description anybody here wrote about what the feature flag does. All feature flags.