style(bridge,mcp): adopt the lean tool-docstring convention for peek/decisions

Rebase adaptation onto main, which rewrote every tool docstring to drop
the Returns: block (the model reads the result shape from the call
itself) in favor of a one-line Errors: list of behavioural error codes.
peek()/decisions() on both the stdio bridge and the in-process MCP
server were still on the old verbose style; bring them in line so the
bridge/http parity guard keeps comparing apples to apples.

Also consolidates CHANGELOG.md's [Unreleased] section, which after the
rebase carried two separate Added headings (one from main, one from
this branch) — merged into one, alongside main's existing Fixed and
Changed buckets.

Author: obeone

CHANGELOG.md

@@ -88,6 +88,10 @@ and rename that heading to the version when you cut the release.
   either abandoning the clear or hanging indefinitely. (`HubConnector.ping`/
   `set_status` already existed; only the auto-status wiring around
   `_drive_turn` is new.)
+- **`docs/operating-cheaply.md`**, on running an agent from a passive,
+  turn-based MCP host without wasting turns: the cost model, what the peer
+  queue does and does not guarantee, the three listening strategies, and
+  when to batch questions.
 
 ### Changed
 
@@ -180,13 +184,6 @@ and rename that heading to the version when you cut the release.
   Connected bridges will see `protocol_stale` on their next `join` and re-read
   the text once, as designed.
 
-### Added
-
-- **`docs/operating-cheaply.md`**, on running an agent from a passive,
-  turn-based MCP host without wasting turns: the cost model, what the peer queue
-  does and does not guarantee, the three listening strategies, and when to batch
-  questions.
-
 ## [2.3.1](https://github.com/obeone/caucus-mcp/compare/v2.3.0...v2.3.1) (2026-08-03)
 
 ### Fixed

src/caucus/mcp_bridge.py

@@ -598,9 +598,7 @@ def ping(peer: str) -> dict[str, object]:
 def peek() -> dict[str, object]:
     """Check whether anything is waiting for you without draining it — a cheap "worth a turn?" probe. Requires join.
 
-    Returns:
-        ``{"pending": <int>, "last": {"sender", "preview"} | None}``, or the
-        usual ``not_joined`` gate error.
+    Errors: ``not_joined``.
     """
     gate = _ensure_armed()
     if gate is not None:
@@ -886,19 +884,12 @@ def list_forms() -> dict[str, object]:
 @mcp.tool()
 @_resilient_hub_call
 def decisions(limit: int = 20) -> dict[str, object]:
-    """List recently settled operator-form decisions, oldest first — catch up without replaying the transcript. Requires join.
-
-    Scoped to broadcast decisions plus those addressed to a channel you
-    currently belong to, same as the audience a channel-scoped answer
-    would itself have reached over listen().
+    """List recently settled operator-form decisions, oldest first — catch up without replaying the transcript. Scoped to broadcast plus channels you belong to. Requires join.
 
     Args:
         limit: Maximum number of decisions to return (the most recent ones).
 
-    Returns:
-        ``{"decisions": [{"ts", "asker", "title", "status",
-        "answer_summary"}, ...]}``, the usual ``not_joined`` gate error, or
-        ``{"error": "hub_unreachable", ...}``.
+    Errors: ``not_joined``.
     """
     gate = _ensure_armed()
     if gate is not None:

src/caucus/mcp_http.py

@@ -808,9 +808,7 @@ async def ping(ctx: _Ctx, peer: str) -> dict[str, object]:
     async def peek(ctx: _Ctx) -> dict[str, object]:
         """Check whether anything is waiting for you without draining it — a cheap "worth a turn?" probe. Requires join.
 
-        Returns:
-            ``{"pending": <int>, "last": {"sender", "preview"} | None}``, or
-            the usual ``not_joined`` gate error.
+        Errors: ``not_joined``.
         """
         member, gate = await _ensure_armed(ctx)
         if gate is not None:
@@ -1081,19 +1079,12 @@ async def list_forms(ctx: _Ctx) -> dict[str, object]:
     @_resilient
     async def decisions(        ctx: _Ctx, limit: int = 20
     ) -> dict[str, object]:
-        """List recently settled operator-form decisions, oldest first — catch up without replaying the transcript. Requires join.
-
-        Scoped to broadcast decisions plus those addressed to a channel you
-        currently belong to, same as the audience a channel-scoped answer
-        would itself have reached over listen().
+        """List recently settled operator-form decisions, oldest first — catch up without replaying the transcript. Scoped to broadcast plus channels you belong to. Requires join.
 
         Args:
             limit: Maximum number of decisions to return (the most recent ones).
 
-        Returns:
-            ``{"decisions": [{"ts", "asker", "title", "status",
-            "answer_summary"}, ...]}``, the usual ``not_joined`` gate error, or
-            ``{"error": "hub_unreachable", ...}``.
+        Errors: ``not_joined``.
         """
         member, gate = await _ensure_armed(ctx)
         if gate is not None: