diff --git a/internal/auth/oauth.go b/internal/auth/oauth.go
index 276b7b2..849b34c 100644
--- a/internal/auth/oauth.go
+++ b/internal/auth/oauth.go
@@ -6,6 +6,7 @@ import (
 	"encoding/hex"
 	"encoding/json"
 	"fmt"
+	"html"
 	"io"
 	"log/slog"
 	"net/http"
@@ -109,7 +110,7 @@ func NewCallbackHandler(expectedState string, codeCh chan<- string, errCh chan<-
 		if stravaErr := query.Get("error"); stravaErr != "" {
 			errCh <- fmt.Errorf("Strava authorization error: %s", stravaErr)
 			w.WriteHeader(http.StatusBadRequest)
-			fmt.Fprintf(w, errorPageHTML, stravaErr)
+			fmt.Fprintf(w, errorPageHTML, html.EscapeString(stravaErr))
 			return
 		}
 
diff --git a/internal/config/config.go b/internal/config/config.go
index 5020006..37f6974 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -11,7 +11,6 @@ type Config struct {
 	ClientID     string
 	ClientSecret string
 	TokenPath    string
-	Debug        bool
 }
 
 // Load reads configuration from environment variables and returns a Config.
diff --git a/internal/server/server.go b/internal/server/server.go
index 7099512..b227803 100644
--- a/internal/server/server.go
+++ b/internal/server/server.go
@@ -7,7 +7,6 @@ import (
 )
 
 // New creates a new MCP server with the given version string and Strava client.
-// Tools are registered via tools.RegisterAll (empty in Phase 1, populated in Phase 2).
 func New(version string, client *strava.Client) *mcpserver.MCPServer {
 	s := mcpserver.NewMCPServer(
 		"strava-mcp",
diff --git a/internal/strava/client.go b/internal/strava/client.go
index a5d1aaf..bbec00b 100644
--- a/internal/strava/client.go
+++ b/internal/strava/client.go
@@ -91,29 +91,30 @@ func (c *Client) Get(ctx context.Context, path string, params map[string]string)
 
 // Post makes an authenticated POST request to the Strava API.
 func (c *Client) Post(ctx context.Context, path string, body interface{}) ([]byte, error) {
-	fullURL := c.baseURL + path
-	jsonBody, err := json.Marshal(body)
-	if err != nil {
-		return nil, fmt.Errorf("marshal request body: %w", err)
-	}
-	return c.doRequest(ctx, http.MethodPost, fullURL, bytes.NewReader(jsonBody), "application/json")
+	return c.jsonRequest(ctx, http.MethodPost, path, body)
 }
 
 // Put makes an authenticated PUT request to the Strava API.
 func (c *Client) Put(ctx context.Context, path string, body interface{}) ([]byte, error) {
-	fullURL := c.baseURL + path
+	return c.jsonRequest(ctx, http.MethodPut, path, body)
+}
+
+func (c *Client) jsonRequest(ctx context.Context, method, path string, body interface{}) ([]byte, error) {
 	jsonBody, err := json.Marshal(body)
 	if err != nil {
 		return nil, fmt.Errorf("marshal request body: %w", err)
 	}
-	return c.doRequest(ctx, http.MethodPut, fullURL, bytes.NewReader(jsonBody), "application/json")
+	return c.doRequest(ctx, method, c.baseURL+path, jsonBody, "application/json")
 }
 
 // PostMultipart makes an authenticated POST request with a pre-built multipart body.
 // The contentType must include the multipart boundary (use writer.FormDataContentType()).
 func (c *Client) PostMultipart(ctx context.Context, path string, body io.Reader, contentType string) ([]byte, error) {
-	fullURL := c.baseURL + path
-	return c.doRequest(ctx, http.MethodPost, fullURL, body, contentType)
+	bodyBytes, err := io.ReadAll(body)
+	if err != nil {
+		return nil, fmt.Errorf("buffer multipart body: %w", err)
+	}
+	return c.doRequest(ctx, http.MethodPost, c.baseURL+path, bodyBytes, contentType)
 }
 
 // GetRateLimits returns the current rate limit state.
@@ -146,7 +147,8 @@ func (c *Client) SetTokenURL(u string) {
 }
 
 // doRequest executes an authenticated HTTP request with automatic token refresh.
-func (c *Client) doRequest(ctx context.Context, method, fullURL string, body io.Reader, contentType string) ([]byte, error) {
+// The body is accepted as []byte so it can be replayed on 401 retry without re-reading.
+func (c *Client) doRequest(ctx context.Context, method, fullURL string, body []byte, contentType string) ([]byte, error) {
 	tokens, err := c.tokenStore.Read()
 	if err != nil {
 		return nil, fmt.Errorf("read tokens: %w", err)
@@ -160,7 +162,14 @@ func (c *Client) doRequest(ctx context.Context, method, fullURL string, body io.
 		}
 	}
 
-	respBody, err := c.executeRequest(ctx, method, fullURL, body, contentType, tokens.AccessToken)
+	bodyReader := func() io.Reader {
+		if body == nil {
+			return nil
+		}
+		return bytes.NewReader(body)
+	}
+
+	respBody, err := c.executeRequest(ctx, method, fullURL, bodyReader(), contentType, tokens.AccessToken)
 	if err != nil {
 		// Check for 401 — retry once after refresh
 		var stravaErr *StravaError
@@ -169,8 +178,8 @@ func (c *Client) doRequest(ctx context.Context, method, fullURL string, body io.
 			if refreshErr != nil {
 				return nil, fmt.Errorf("token refresh after 401: %w", refreshErr)
 			}
-			// Retry with new token — if this also fails, return the error directly
-			return c.executeRequest(ctx, method, fullURL, body, contentType, tokens.AccessToken)
+			// Retry with new token and a fresh reader
+			return c.executeRequest(ctx, method, fullURL, bodyReader(), contentType, tokens.AccessToken)
 		}
 		return nil, err
 	}
diff --git a/internal/strava/client_test.go b/internal/strava/client_test.go
index 543ec08..2ae77df 100644
--- a/internal/strava/client_test.go
+++ b/internal/strava/client_test.go
@@ -616,6 +616,70 @@ func TestPostMultipartReturnsStravaErrorOn4xx(t *testing.T) {
 	}
 }
 
+// Test 14: Post() replays full body on 401 retry (regression test for body-reuse bug)
+func TestPostReplaysBodyOn401Retry(t *testing.T) {
+	var requestCount atomic.Int32
+	var bodies []string
+	var mu sync.Mutex
+
+	apiSrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		body, _ := io.ReadAll(r.Body)
+		mu.Lock()
+		bodies = append(bodies, string(body))
+		mu.Unlock()
+
+		count := requestCount.Add(1)
+		if count == 1 {
+			w.WriteHeader(http.StatusUnauthorized)
+			w.Write([]byte(`{"message":"Authorization Error"}`))
+			return
+		}
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`{"id":123}`))
+	}))
+	defer apiSrv.Close()
+
+	tokenSrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		json.NewEncoder(w).Encode(auth.Tokens{
+			AccessToken:  "refreshed-token",
+			RefreshToken: "new-refresh",
+			ExpiresAt:    time.Now().Add(6 * time.Hour).Unix(),
+		})
+	}))
+	defer tokenSrv.Close()
+
+	store := newMockTokenStore(&auth.Tokens{
+		AccessToken:  "stale-token",
+		RefreshToken: "refresh-token",
+		ExpiresAt:    time.Now().Add(1 * time.Hour).Unix(),
+	}, false)
+
+	cfg := &config.Config{ClientID: "id", ClientSecret: "secret"}
+	client := strava.NewClient(cfg, store, testLogger())
+	client.SetBaseURL(apiSrv.URL)
+	client.SetTokenURL(tokenSrv.URL)
+
+	payload := map[string]string{"name": "Morning Run", "description": "Easy 5K"}
+	_, err := client.Post(context.Background(), "/activities", payload)
+	if err != nil {
+		t.Fatalf("Post() error: %v", err)
+	}
+
+	if requestCount.Load() != 2 {
+		t.Fatalf("API requests = %d, want 2 (initial + retry)", requestCount.Load())
+	}
+
+	// Both requests must have received the full JSON body
+	for i, body := range bodies {
+		if !strings.Contains(body, "Morning Run") {
+			t.Errorf("request %d body = %q, want to contain 'Morning Run'", i+1, body)
+		}
+		if !strings.Contains(body, "Easy 5K") {
+			t.Errorf("request %d body = %q, want to contain 'Easy 5K'", i+1, body)
+		}
+	}
+}
+
 // TestNewClientReturnsNonNil verifies the constructor works
 func TestNewClientReturnsNonNil(t *testing.T) {
 	dir := t.TempDir()
diff --git a/internal/tools/activities.go b/internal/tools/activities.go
index b6da55b..7f10fc4 100644
--- a/internal/tools/activities.go
+++ b/internal/tools/activities.go
@@ -11,8 +11,6 @@ import (
 	"github.com/Stealinglight/StravaMCP/internal/strava"
 )
 
-// --- Tool Definitions ---
-
 var getActivitiesTool = mcp.NewTool("strava_get_activities",
 	mcp.WithDescription(`Retrieves the authenticated athlete's activities.
 
@@ -161,8 +159,6 @@ Useful for:
 	mcp.WithNumber("id", mcp.Description("The ID of the activity"), mcp.Required()),
 )
 
-// --- Handler Functions ---
-
 // HandleGetActivities returns a handler for the get_activities tool.
 func HandleGetActivities(client *strava.Client) server.ToolHandlerFunc {
 	return func(ctx context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) {
@@ -241,21 +237,10 @@ func HandleCreateActivity(client *strava.Client) server.ToolHandlerFunc {
 			"elapsed_time":     elapsedTime,
 		}
 
-		// Optional fields
-		if v, ok := args["type"]; ok {
-			body["type"] = v
-		}
-		if v, ok := args["description"]; ok {
-			body["description"] = v
-		}
-		if v, ok := args["distance"]; ok {
-			body["distance"] = v
-		}
-		if v, ok := args["trainer"]; ok {
-			body["trainer"] = v
-		}
-		if v, ok := args["commute"]; ok {
-			body["commute"] = v
+		for _, field := range []string{"type", "description", "distance", "trainer", "commute"} {
+			if v, ok := args[field]; ok {
+				body[field] = v
+			}
 		}
 
 		data, err := client.Post(ctx, "/activities", body)
@@ -318,8 +303,6 @@ func HandleGetActivityZones(client *strava.Client) server.ToolHandlerFunc {
 	}
 }
 
-// --- Registration ---
-
 // registerActivities registers all activity tools with the MCP server.
 func registerActivities(s *server.MCPServer, client *strava.Client) {
 	s.AddTool(getActivitiesTool, HandleGetActivities(client))
diff --git a/internal/tools/athlete.go b/internal/tools/athlete.go
index 2b7af32..c7de34b 100644
--- a/internal/tools/athlete.go
+++ b/internal/tools/athlete.go
@@ -11,8 +11,6 @@ import (
 	"github.com/Stealinglight/StravaMCP/internal/strava"
 )
 
-// --- Tool Definitions ---
-
 var getAthleteTool = mcp.NewTool("strava_get_athlete",
 	mcp.WithDescription(`Retrieves the authenticated athlete's profile information.
 
@@ -75,8 +73,6 @@ Statistics include:
 	mcp.WithNumber("id", mcp.Description("Athlete ID (optional - defaults to authenticated athlete)")),
 )
 
-// --- Handler Functions ---
-
 // HandleGetAthlete returns a handler for the get_athlete tool.
 func HandleGetAthlete(client *strava.Client) server.ToolHandlerFunc {
 	return func(ctx context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) {
@@ -118,8 +114,6 @@ func HandleGetAthleteStats(client *strava.Client) server.ToolHandlerFunc {
 	}
 }
 
-// --- Registration ---
-
 // registerAthlete registers all athlete tools with the MCP server.
 func registerAthlete(s *server.MCPServer, client *strava.Client) {
 	s.AddTool(getAthleteTool, HandleGetAthlete(client))
diff --git a/internal/tools/clubs.go b/internal/tools/clubs.go
index 26291e6..922de6a 100644
--- a/internal/tools/clubs.go
+++ b/internal/tools/clubs.go
@@ -11,8 +11,6 @@ import (
 	"github.com/Stealinglight/StravaMCP/internal/strava"
 )
 
-// --- Tool Definition ---
-
 var getClubActivitiesTool = mcp.NewTool("strava_get_club_activities",
 	mcp.WithDescription(`Retrieves recent activities from members of a specific club.
 
@@ -44,8 +42,6 @@ Note: Only shows activities from club members who have their privacy settings se
 	mcp.WithNumber("per_page", mcp.Description("Number of items per page (1-200, default 30)")),
 )
 
-// --- Handler Function ---
-
 // HandleGetClubActivities returns a handler for the get_club_activities tool.
 func HandleGetClubActivities(client *strava.Client) server.ToolHandlerFunc {
 	return func(ctx context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) {
@@ -71,8 +67,6 @@ func HandleGetClubActivities(client *strava.Client) server.ToolHandlerFunc {
 	}
 }
 
-// --- Registration ---
-
 // registerClubs registers all club tools with the MCP server.
 func registerClubs(s *server.MCPServer, client *strava.Client) {
 	s.AddTool(getClubActivitiesTool, HandleGetClubActivities(client))
diff --git a/internal/tools/helpers.go b/internal/tools/helpers.go
index bd58773..9f31ba0 100644
--- a/internal/tools/helpers.go
+++ b/internal/tools/helpers.go
@@ -21,7 +21,7 @@ func FormatResponse(data []byte, client *strava.Client) *mcp.CallToolResult {
 
 	result := pretty.String()
 
-	// Append rate limit warning if usage is high (D-02)
+	// Append rate limit warning if usage is high
 	if warning := client.RateLimitWarning(); warning != "" {
 		result += "\n\n" + warning
 	}
diff --git a/internal/tools/register.go b/internal/tools/register.go
index b6478b6..04bace2 100644
--- a/internal/tools/register.go
+++ b/internal/tools/register.go
@@ -6,12 +6,6 @@ import (
 )
 
 // RegisterAll registers all MCP tools with the server.
-// Registers 11 tools across 5 resource categories:
-// - Activities: strava_get_activities, strava_get_activity_by_id, strava_create_activity, strava_update_activity, strava_get_activity_zones
-// - Athlete: strava_get_athlete, strava_get_athlete_stats
-// - Streams: strava_get_activity_streams
-// - Clubs: strava_get_club_activities
-// - Uploads: strava_create_upload, strava_get_upload
 func RegisterAll(s *server.MCPServer, client *strava.Client) {
 	registerActivities(s, client)
 	registerAthlete(s, client)
diff --git a/internal/tools/streams.go b/internal/tools/streams.go
index 70586de..9630edd 100644
--- a/internal/tools/streams.go
+++ b/internal/tools/streams.go
@@ -18,8 +18,6 @@ var streamTypes = []string{
 	"heartrate", "cadence", "watts", "temp", "moving", "grade_smooth",
 }
 
-// --- Tool Definition ---
-
 var getActivityStreamsTool = mcp.NewTool("strava_get_activity_streams",
 	mcp.WithDescription(`**[TELEMETRY & DEEP ANALYSIS]** Retrieves time-series sensor data (streams) from an activity.
 
@@ -100,8 +98,6 @@ var getActivityStreamsTool = mcp.NewTool("strava_get_activity_streams",
 	mcp.WithBoolean("key_by_type", mcp.Description("Return streams as an object keyed by type (default: true)")),
 )
 
-// --- Handler Function ---
-
 // HandleGetActivityStreams returns a handler for the get_activity_streams tool.
 func HandleGetActivityStreams(client *strava.Client) server.ToolHandlerFunc {
 	return func(ctx context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) {
@@ -141,8 +137,6 @@ func HandleGetActivityStreams(client *strava.Client) server.ToolHandlerFunc {
 	}
 }
 
-// --- Registration ---
-
 // registerStreams registers all streams tools with the MCP server.
 func registerStreams(s *server.MCPServer, client *strava.Client) {
 	s.AddTool(getActivityStreamsTool, HandleGetActivityStreams(client))
diff --git a/internal/tools/uploads.go b/internal/tools/uploads.go
index afcad1f..fc6bb27 100644
--- a/internal/tools/uploads.go
+++ b/internal/tools/uploads.go
@@ -17,8 +17,6 @@ import (
 	"github.com/Stealinglight/StravaMCP/internal/strava"
 )
 
-// --- Tool Definitions ---
-
 var createUploadTool = mcp.NewTool("strava_create_upload",
 	mcp.WithDescription(`Uploads a new activity file to Strava.
 
@@ -106,8 +104,6 @@ After an athlete uploads a workout file:
 	mcp.WithNumber("id", mcp.Description("The ID of the upload"), mcp.Required()),
 )
 
-// --- Handler Functions ---
-
 // validDataTypes lists all valid upload data types.
 var validDataTypes = map[string]bool{
 	"fit": true, "tcx": true, "gpx": true,
@@ -220,8 +216,6 @@ func HandleGetUpload(client *strava.Client) server.ToolHandlerFunc {
 	}
 }
 
-// --- Registration ---
-
 // registerUploads registers all upload tools with the MCP server.
 func registerUploads(s *server.MCPServer, client *strava.Client) {
 	s.AddTool(createUploadTool, HandleCreateUpload(client))