{"version":"2.1.281","anchor":"tool-schemas-can-be-sent-straight-from-the-recorded-prompt-s","canonical_anchor":"tool-schemas-can-be-sent-straight-from-the-recorded-prompt-s","heading":"Tool schemas can be sent straight from the recorded prompt snapshot (tengu_binary_balloon, off by default)","tier":"soon","area":"Models","url":"https:\/\/changelogs.core-directive.com\/v\/2.1.281\/e\/tool-schemas-can-be-sent-straight-from-the-recorded-prompt-s","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.281","markdown":"### Tool schemas can be sent straight from the recorded prompt snapshot (tengu_binary_balloon, off by default)\n\nRemote sessions can send tool descriptions straight from a recorded snapshot instead of rebuilding them, behind tengu_binary_balloon\n\n**Unclear.** The finding does not say what the unnamed internal condition checks.\n\n**What**\n\nEach tool Claude Code offers the model comes with a description and an `input_schema`, which is the list of inputs the tool accepts. A new path can send these straight from a recorded prompt snapshot, a saved copy of an earlier prompt, instead of rebuilding the tool. It is used only when all of these hold:\n\n- `CLAUDE_CODE_REMOTE`: this is set\n\n- a further internal check passes\n\n- there is no strict schema\n\n- there are no describe hooks, meaning no custom code that rewrites the tool description\n\n- `tengu_binary_balloon`: this gate is on\n\nWhen the path is used, Claude Code logs `prompt_snapshot_tool_build_skip_flag` and a batched `prompt_snapshot_tool_build_skipped` event with counts of skipped tools and skipped MCP tools. The code deciding whether tool inputs stream to the model early was moved into its own helper without changing how it works, still using `tengu_fgts` and the `eagerInputStreaming` setting for Vertex and Bedrock. For `tengu_binary_balloon`, the flag server returned off for this site's account and for an anonymous account.\n\n**Why**\n\nSkipping the rebuild saves work at the start of a request in remote sessions. It only takes effect where the gate is switched on, so most users will see no difference.\n\n- Flag `tengu_binary_balloon`: Off in both readings (read for one account on one subscription tier against v2.1.281; this account: off, anonymous baseline: off, compiled default: 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.\n- Flag `tengu_fgts`: Off by default, switched on for this account (read for one account on one subscription tier against v2.1.281; this account: on, anonymous baseline: on, compiled default: 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.\n- Area: Models\n- Tier: Nothing to try yet\n- Useful: 2\/5\n- Signal: 3\/5\n- Present in the build but not switched on"}