docs(rfd): Add RFD 107 discoverable tools

docs/rfd/078-tool-config-mutation.md

@@ -5,6 +5,7 @@
 - **Authors**: Jean Mertz <git@jeanmertz.com>
 - **Date**: 2026-04-17
 - **Requires**: [RFD 076], [RFD 070]
+- **Extended by**: [RFD 107]
 - **Summary**: Scoped tool config access via `access.config` rules, with
   re-invocation on delta rejection and per-cycle commit buffering.
 
@@ -1300,3 +1301,4 @@ Depends on: Phase 2.
 [RFD 042]: 042-tool-options.md
 [RFD 070]: 070-negative-config-deltas.md
 [RFD 076]: 076-tool-access-grants.md
+[RFD 107]: 108-discoverable-tools.md

docs/rfd/081-decompose-tool-enable-into-state-and-allow_toggle.md

@@ -5,6 +5,7 @@
 - **Authors**: Jean Mertz <git@jeanmertz.com>
 - **Date**: 2026-05-11
 - **Extends**: [RFD 008]
+- **Extended by**: [RFD 107]
 - **Summary**: Split tool enable into state and allow_toggle to fix directive
   bugs and eliminate variant proliferation.
 
@@ -885,3 +886,4 @@ Phase 4 (tests and RFD updates) lands in the same PR.
 [RFD 078]: 078-tool-config-mutation.md
 [RFD 079]: 079-config-sources-and-load-order.md
 [RFD 083]: 083-built-in-ask_user-tool-for-assistant-initiated-inquiries.md
+[RFD 107]: 108-discoverable-tools.md

docs/rfd/105-mid-conversation-operator-directives.md

@@ -209,6 +209,14 @@ but it cannot *withdraw* a tool, and it answers a different question: which
 tools should the model pick from a large uncurated catalogue.
 Deferred to its own RFD.
 
+That deferral is not neutral, and the follow-up should know why.
+This RFD leaves discovery nowhere to operate: the initial directive offers every
+enabled tool and withdraws every disabled one, so a reference to an enabled tool
+is a no-op and a reference to a disabled one bypasses the user's intent.
+Discovery becomes meaningful only once tool enablement grows a third state — in
+the catalogue, permitted, not offered until the model asks for it.
+Designing that state, not the search itself, is the follow-up's real work.
+
 **Unify on `tool_reference` and drop directives.** Rejected: there is no
 "unreference" block, so mid-conversation disabling would still rewrite the
 prefix.