{"version":"2.1.248","anchor":"mcp-tools-routed-through-the-repl-instead-of-the-tool-list-s","canonical_anchor":"mcp-tools-routed-through-the-repl-instead-of-the-tool-list-s","heading":"MCP tools routed through the REPL instead of the tool list, switched off","tier":"soon","area":"MCP","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.248\/e\/mcp-tools-routed-through-the-repl-instead-of-the-tool-list-s","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.248","markdown":"### MCP tools routed through the REPL instead of the tool list, switched off\n\nMCP tools could be called from inside the REPL rather than listed as top-level tools.\n\n**What**\n\nGroundwork is present for a mode in which tools from connected MCP servers (external tool servers Claude Code connects to) are called from inside the REPL environment rather than advertised as top-level tools. The predicate that selects this mode is a function whose whole body returns false, so the filter never fires and the wait-for-servers tool always emits the existing wording, \"The server's tools should now be available.\" and \"its tools will be added to your tool list\". The alternative phrasing describing REPL-callable tools is compiled in but unreachable.\n\n**Details**\n\n- MCP authentication stub tools are now tagged `isAuthStub: !0` in their server info, a field absent from 2.1.247.\n- Two new helpers read that tag: one narrows a tool list to non-MCP tools plus auth stubs, the other decides whether MCP tools stay deferrable and whether callers pass `keepMcp`.\n- The REPL surface itself is gated on `tengu_slate_harbor`, which falls back to false, and applies only to the `cli` and `remote` entrypoints.\n- The wait tool still returns `ready=true` on the existing path, so no behaviour visible to users changes in this build.\n\n**Evidence**\n\n`rather than advertising them as top-level tools). Returns ready=true when`, `callable inside the REPL environment (this surface routes MCP tools through the REPL rather than advertising them as top-level tools)`, `The server's tools should now be available.`, `tengu_slate_harbor`, `isAuthStub`, `keepMcp`\n\n- Flag `tengu_slate_harbor`: Not enough to say (read for one account on one subscription tier against v2.1.248; this account: no value returned, anonymous baseline: no value returned, compiled default: off)\n- Area: MCP\n- Tier: Nothing to try yet\n- Useful: 2\/5\n- Signal: 4\/5\n- Present in the build but not switched on"}