fix: v0.2.7 — remove -> str annotations and trim docstrings to reduce tools/list payload

FastMCP generates outputSchema for every tool with a return annotation,
roughly doubling the tools/list payload size. Multi-line docstrings with
Args/Returns sections add further bulk that Claude Desktop must parse.

- Strip -> str from all 23 @mcp.tool() functions
- Trim every tool docstring to a single descriptive line (≤100 chars)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/mcp_synology_container/modules/images.py

@@ -102,12 +102,8 @@ def register_images(mcp: FastMCP, config: AppConfig, client: DsmClient) -> None:
     """Register all image management tools with the MCP server."""
 
     @mcp.tool()
-    async def list_images() -> str:
-        """List all local Docker images sorted by size (largest first).
-
-        Shows name:tag, size, creation date, and whether the image is
-        currently used by at least one container.
-        """
+    async def list_images():
+        """List local Docker images sorted by size, showing tag, date, and in-use status."""
         try:
             img_data = await client.request(
                 "SYNO.Docker.Image",
@@ -156,18 +152,8 @@ def register_images(mcp: FastMCP, config: AppConfig, client: DsmClient) -> None:
         return "\n".join(lines)
 
     @mcp.tool()
-    async def delete_image(image_id: str, confirmed: bool = False) -> str:
-        """Delete a local Docker image by name:tag or image ID hash.
-
-        Without confirmed=True, returns a preview of what would be deleted.
-        Refuses deletion if the image is used by any container.
-
-        Args:
-            image_id: Image reference as "name:tag" (e.g. "nginx:1.24")
-                      or a full/short image hash (e.g. "sha256:14300de7…").
-            confirmed: Must be True to actually delete. Default False shows
-                       a preview only.
-        """
+    async def delete_image(image_id: str, confirmed: bool = False):
+        """Delete a local image by name:tag or hash. Requires confirmed=True; refuses if in use."""
         # Parse name and tag using the last ":" as separator so that
         # registry-prefixed images (e.g. "ghcr.io/foo/bar:v1") are handled
         # correctly.  rpartition returns ("", "", original) when ":" is absent.
@@ -284,16 +270,8 @@ def register_images(mcp: FastMCP, config: AppConfig, client: DsmClient) -> None:
         return f"Deleted {display_name} — {size_str} freed."
 
     @mcp.tool()
-    async def check_image_updates(project_name: str | None = None) -> str:
-        """Check for available image updates for a project or all images.
-
-        Queries the local image list and reports which images have the
-        'upgradable' flag set by the NAS registry check.
-
-        Args:
-            project_name: Optional project name to filter images.
-                          If omitted, checks all locally available images.
-        """
+    async def check_image_updates(project_name: str | None = None):
+        """Check which local images have updates available (upgradable flag from NAS registry)."""
         try:
             data = await client.request(
                 "SYNO.Docker.Image",