refactor: migrate tool outputs to use EmbeddedResource with typed JSON for assistant-facing data

docs/DESIGN_DECISIONS.md

@@ -21,12 +21,12 @@ This document records key architectural and design decisions made during the dev
 - Initial authentication is handled via a separate `auth` script or integrated OAuth flow.
 
 ## 3. Data Representation & MCP Annotations
-**Decision**: Use dual-content outputs with audience-specific annotations.
-**Context**: To provide a clean user experience while giving the LLM detailed data, we split tool results into two parts.
+**Decision**: Use dual-content outputs with audience-specific annotations and native MIME typing.
+**Context**: To provide a clean user experience while giving the LLM detailed data, we split tool results into two parts and use protocol-level typing.
 **Implementation**:
-- **User Facing**: Markdown summaries annotated with `audience=["user"]`.
-- **Assistant Facing**: Raw JSON data annotated with `audience=["assistant"]`.
-- This allows MCP clients to intelligently decide what to display to the user while ensuring the assistant receives full technical context.
+- **User Facing**: Markdown summaries annotated with `audience=["user"]` using `TextContent`.
+- **Assistant Facing**: Raw JSON data provided as an `EmbeddedResource` with `mimeType="application/json"` and annotated with `audience=["assistant"]`.
+- This ensures the LLM explicitly knows the data format while allowing clients to optimize the user-facing UI.
 
 ## 4. Internationalization
 **Decision**: Use metric units (meters, km, m/s) internally and provide clear conversion instructions to the LLM.

src/strava_mcp_server/tools/activities.py

@@ -1,6 +1,6 @@
 import json
 from mcp.server.fastmcp import FastMCP, Context
-from mcp.types import TextContent, Annotations
+from mcp.types import ContentBlock, TextContent, Annotations, EmbeddedResource, TextResourceContents
 from strava_mcp_server.strava_client import StravaClient
 from strava_mcp_server.utils import parse_iso_to_unix, format_date_iso, format_date_human
 
@@ -12,7 +12,7 @@ def register(mcp: FastMCP, strava: StravaClient) -> None:
         page: int = 1,
         before: str | None = None,
         after: str | None = None,
-    ) -> list[TextContent]:
+    ) -> list[ContentBlock]:
         """
         List recent Strava activities for the authenticated user.
         :param limit: Number of activities to return per page (default 10, max 200).
@@ -62,9 +62,13 @@ def register(mcp: FastMCP, strava: StravaClient) -> None:
                     text=markdown_summary.strip(),
                     annotations=Annotations(audience=["user"])
                 ),
-                TextContent(
-                    type="text", 
-                    text=json.dumps(essential_data, indent=2),
+                EmbeddedResource(
+                    type="resource",
+                    resource=TextResourceContents(
+                        uri="internal://activities/list",
+                        mimeType="application/json",
+                        text=json.dumps(essential_data, indent=2)
+                    ),
                     annotations=Annotations(audience=["assistant"])
                 )
             ]

src/strava_mcp_server/tools/athlete.py

@@ -1,12 +1,12 @@
 import json
 from mcp.server.fastmcp import FastMCP, Context
-from mcp.types import TextContent, Annotations
+from mcp.types import ContentBlock, TextContent, Annotations, EmbeddedResource, TextResourceContents
 from strava_mcp_server.strava_client import StravaClient
 from strava_mcp_server.utils import format_date_iso, format_date_human
 
 def register(mcp: FastMCP, strava: StravaClient) -> None:
     @mcp.tool()
-    async def get_athlete_profile(ctx: Context) -> list[TextContent]:
+    async def get_athlete_profile(ctx: Context) -> list[ContentBlock]:
         """
         Get the authenticated Strava athlete's profile.
         Returns name, city, country, follower count, and other profile details.
@@ -56,9 +56,13 @@ def register(mcp: FastMCP, strava: StravaClient) -> None:
                     text=markdown_summary,
                     annotations=Annotations(audience=["user"])
                 ),
-                TextContent(
-                    type="text", 
-                    text=json.dumps(essential_data, indent=2),
+                EmbeddedResource(
+                    type="resource",
+                    resource=TextResourceContents(
+                        uri="internal://athlete/profile",
+                        mimeType="application/json",
+                        text=json.dumps(essential_data, indent=2)
+                    ),
                     annotations=Annotations(audience=["assistant"])
                 )
             ]
@@ -69,7 +73,7 @@ def register(mcp: FastMCP, strava: StravaClient) -> None:
             return [TextContent(type="text", text=error_msg)]
 
     @mcp.tool()
-    async def get_athlete_zones(ctx: Context) -> list[TextContent]:
+    async def get_athlete_zones(ctx: Context) -> list[ContentBlock]:
         """
         Get the heart rate and power zones configured for the authenticated athlete.
         Returns zone boundaries for both heart rate and power (if a power meter is configured).
@@ -108,9 +112,13 @@ def register(mcp: FastMCP, strava: StravaClient) -> None:
                     text=markdown_summary.strip(),
                     annotations=Annotations(audience=["user"])
                 ),
-                TextContent(
-                    type="text", 
-                    text=json.dumps(zones, indent=2),
+                EmbeddedResource(
+                    type="resource",
+                    resource=TextResourceContents(
+                        uri="internal://athlete/zones",
+                        mimeType="application/json",
+                        text=json.dumps(zones, indent=2)
+                    ),
                     annotations=Annotations(audience=["assistant"])
                 )
             ]
@@ -120,7 +128,7 @@ def register(mcp: FastMCP, strava: StravaClient) -> None:
             return [TextContent(type="text", text=error_msg)]
 
     @mcp.tool()
-    async def get_athlete_stats(ctx: Context) -> list[TextContent]:
+    async def get_athlete_stats(ctx: Context) -> list[ContentBlock]:
         """
         Get cumulative training statistics for the authenticated Strava athlete.
         Includes all-time, year-to-date, and recent (4-week) totals for runs, rides, and swims.
@@ -175,9 +183,13 @@ def register(mcp: FastMCP, strava: StravaClient) -> None:
                     text=markdown_summary.strip(),
                     annotations=Annotations(audience=["user"])
                 ),
-                TextContent(
-                    type="text", 
-                    text=json.dumps(stats, indent=2),
+                EmbeddedResource(
+                    type="resource",
+                    resource=TextResourceContents(
+                        uri="internal://athlete/stats",
+                        mimeType="application/json",
+                        text=json.dumps(stats, indent=2)
+                    ),
                     annotations=Annotations(audience=["assistant"])
                 )
             ]