feat(meta-tools): guide @mux to optimize minimal-first

Optimizing was slow because the model dumped the whole catalog and built
one large FeatureSet upfront. Add concise (token-cheap) guidance steering
it to start minimal and expand on demand:

- Server instructions: "start minimal, expand later" one-liner.
- mcpmux_list_all_tools: prefer mcpmux_search_tools; flag the full dump as
  token-heavy.
- mcpmux_manage_feature_set: prefer a small initial set expanded later.

Guidance-only; no tool behavior change.

Signed-off-by: Mohammod Al Amin Ashik <maa.ashik00@gmail.com>

Author: its-mash

crates/mcpmux-gateway/src/mcp/handler.rs

@@ -368,7 +368,10 @@ impl ServerHandler for McpMuxGatewayHandler {
              list_feature_sets) are safe to call freely once the user has opted \
              in; writes (manage_feature_set, bind_current_workspace) prompt the \
              user for approval. Most operations accept an optional `space_id` \
-             (from mcpmux_list_spaces) to target a specific Space."
+             (from mcpmux_list_spaces) to target a specific Space. When \
+             optimizing, start minimal: search for the few tools the task needs, \
+             compose a small set, then expand it later as needs arise rather than \
+             dumping the whole catalog upfront."
                 .to_string(),
         );
         info

crates/mcpmux-gateway/src/services/meta_tools/tools.rs

@@ -116,8 +116,8 @@ impl MetaTool for ListAllToolsTool {
     fn description(&self) -> &'static str {
         "List every tool installed in a Space (default: the caller's resolved \
          Space; pass `space_id` to target another), without the current \
-         FeatureSet filter applied. Use this to see what could be exposed \
-         before composing a custom FeatureSet. Returns an array of \
+         FeatureSet filter applied. Prefer `mcpmux_search_tools` unless you need \
+         the full list — this dump is token-heavy. Returns an array of \
          {server_id, qualified_name, description, available}."
     }
 
@@ -716,7 +716,8 @@ impl MetaTool for ManageFeatureSetTool {
          (needs `feature_set_id`). Tool names are the qualified names from \
          `mcpmux_list_all_tools`/`mcpmux_search_tools`. Built-in sets can't be \
          modified. Requires user approval. Route a workspace through a FeatureSet \
-         with `mcpmux_bind_current_workspace`."
+         with `mcpmux_bind_current_workspace`. Prefer a small initial set you \
+         expand later over adding everything upfront."
     }
 
     fn input_schema(&self) -> Value {