diff --git a/docs/tools.md b/docs/tools.md
index 549eaf3..ed699ee 100644
--- a/docs/tools.md
+++ b/docs/tools.md
@@ -145,11 +145,21 @@ Required: `project_id`, `issue_id`.
 
 POST `/projects/{project_id}/issues/{issue_id}/issue-attachments/`.
 
-Low-level: returns `{ id, upload_data: { url, fields: {...} } }`. Use
-`plane_attachment_upload` for the full init → s3 → complete flow.
+Advanced low-level step for custom upload clients. Use `plane_attachment_upload`
+for normal uploads.
 
 Required: `project_id`, `issue_id`, `name`.
-Optional: `file_type` (mime type), `size` (number, bytes).
+Optional: `file_type` (mime type), `size` (number, bytes), `raw` (boolean).
+
+By default, returns compact metadata such as:
+
+```json
+{ "asset_id": "...", "asset_url": "...", "raw_upload_credentials_omitted": true }
+```
+
+With `raw: true`, returns the full Plane init payload, including
+`upload_data.url` and temporary S3 form credential fields needed by custom
+multipart clients.
 
 ### `plane_attachment_complete_upload`
 
diff --git a/internal/mcpserver/server_test.go b/internal/mcpserver/server_test.go
index e914263..4eb5e59 100644
--- a/internal/mcpserver/server_test.go
+++ b/internal/mcpserver/server_test.go
@@ -407,6 +407,91 @@ func TestHealthReturnsStructuredEndpointErrors(t *testing.T) {
 	require.Contains(t, issues["error"], "403")
 }
 
+func TestAttachmentInitUploadSchemaWarnsAboutRawCredentials(t *testing.T) {
+	srv := newTestServer(t, func(w http.ResponseWriter, _ *http.Request) {
+		_, _ = w.Write([]byte(`{}`))
+	})
+	c, err := client.NewInProcessClient(srv.MCPServer())
+	require.NoError(t, err)
+	require.NoError(t, c.Start(context.Background()))
+	t.Cleanup(func() { _ = c.Close() })
+
+	_, err = c.Initialize(context.Background(), mcp.InitializeRequest{})
+	require.NoError(t, err)
+	list, err := c.ListTools(context.Background(), mcp.ListToolsRequest{})
+	require.NoError(t, err)
+
+	for _, tool := range list.Tools {
+		if tool.Name == "plane_attachment_init_upload" {
+			require.Contains(t, tool.Description, "Prefer plane_attachment_upload")
+			require.Contains(t, tool.Description, "temporary S3 form credentials")
+			raw, ok := tool.InputSchema.Properties["raw"].(map[string]any)
+			require.True(t, ok)
+			require.Equal(t, "boolean", raw["type"])
+			require.Contains(t, raw["description"], "temporary S3 upload form credentials")
+			return
+		}
+	}
+	require.Fail(t, "plane_attachment_init_upload should be registered")
+}
+
+func TestAttachmentInitUploadDefaultsToCompactResult(t *testing.T) {
+	srv := newTestServer(t, func(w http.ResponseWriter, r *http.Request) {
+		require.Equal(t, "/api/v1/workspaces/ws/projects/P/issues/I/issue-attachments/", r.URL.Path)
+		_, _ = w.Write([]byte(`{
+			"id": "asset-1",
+			"asset_url": "https://cdn.example.com/file.txt",
+			"name": "file.txt",
+			"upload_data": {
+				"url": "https://uploads.example.com/",
+				"fields": {
+					"key": "tmp/file.txt",
+					"policy": "secret-policy",
+					"x-amz-signature": "secret-signature"
+				}
+			}
+		}`))
+	})
+
+	payload := callToolPayload(t, srv, "plane_attachment_init_upload", map[string]any{
+		"project_id": "P",
+		"issue_id":   "I",
+		"name":       "file.txt",
+	})
+	require.Equal(t, "asset-1", payload["asset_id"])
+	require.Equal(t, "https://cdn.example.com/file.txt", payload["asset_url"])
+	require.Equal(t, "file.txt", payload["name"])
+	require.Equal(t, true, payload["raw_upload_credentials_omitted"])
+	require.Equal(t, true, payload["upload_credentials_available_with_raw"])
+	require.NotContains(t, payload, "upload_data")
+}
+
+func TestAttachmentInitUploadRawReturnsFullPayload(t *testing.T) {
+	srv := newTestServer(t, func(w http.ResponseWriter, r *http.Request) {
+		require.Equal(t, "/api/v1/workspaces/ws/projects/P/issues/I/issue-attachments/", r.URL.Path)
+		_, _ = w.Write([]byte(`{
+			"id": "asset-1",
+			"upload_data": {
+				"url": "https://uploads.example.com/",
+				"fields": {"policy": "secret-policy"}
+			}
+		}`))
+	})
+
+	payload := callToolPayload(t, srv, "plane_attachment_init_upload", map[string]any{
+		"project_id": "P",
+		"issue_id":   "I",
+		"name":       "file.txt",
+		"raw":        true,
+	})
+	require.Equal(t, "asset-1", payload["id"])
+	uploadData, ok := payload["upload_data"].(map[string]any)
+	require.True(t, ok)
+	fields, ok := uploadData["fields"].(map[string]any)
+	require.True(t, ok)
+	require.Equal(t, "secret-policy", fields["policy"])
+}
+
 func TestAttachmentMimeTypeStripsParameters(t *testing.T) {
 	require.Equal(t, "text/plain", attachmentMimeType("notes.txt"))
 	require.Equal(t, "application/octet-stream", attachmentMimeType("archive.unknownext"))
diff --git a/internal/mcpserver/tools_attachments.go b/internal/mcpserver/tools_attachments.go
index 532440b..b812e70 100644
--- a/internal/mcpserver/tools_attachments.go
+++ b/internal/mcpserver/tools_attachments.go
@@ -23,12 +23,13 @@ func (s *Server) registerAttachmentTools() {
 	), s.handleAttachmentList)
 
 	s.mcp.AddTool(mcp.NewTool("plane_attachment_init_upload",
-		mcp.WithDescription("Low-level: request S3 upload credentials for a new attachment."),
+		mcp.WithDescription("Advanced/low-level: request attachment upload metadata. Prefer plane_attachment_upload; raw=true returns temporary S3 form credentials."),
 		mcp.WithString("project_id", mcp.Required()),
 		mcp.WithString("issue_id", mcp.Required()),
 		mcp.WithString("name", mcp.Required()),
 		mcp.WithString("file_type"),
 		mcp.WithNumber("size"),
+		mcp.WithBoolean("raw", mcp.Description("Return the full Plane payload, including temporary S3 upload form credentials.")),
 	), s.handleAttachmentInitUpload)
 
 	s.mcp.AddTool(mcp.NewTool("plane_attachment_complete_upload",
@@ -90,7 +91,10 @@ func (s *Server) handleAttachmentInitUpload(ctx context.Context, req mcp.CallToo
 	if err != nil {
 		return toolError(err), nil
 	}
-	return asTextResult(out)
+	if raw := argBoolPtr(args, "raw"); raw != nil && *raw {
+		return asTextResult(out)
+	}
+	return asTextResult(compactAttachmentInitUpload(out))
 }
 
 func (s *Server) handleAttachmentCompleteUpload(ctx context.Context, req mcp.CallToolRequest) (*mcp.CallToolResult, error) {
@@ -270,6 +274,89 @@ func parseInitPayload(init map[string]any) (assetID, uploadURL string, fields ma
 	return assetID, uploadURL, fields, nil
 }
 
+func compactAttachmentInitUpload(init map[string]any) map[string]any {
+	out := map[string]any{
+		"raw_upload_credentials_omitted": true,
+	}
+	if assetID := initUploadAssetID(init); assetID != "" {
+		out["asset_id"] = assetID
+	}
+	if assetURL := initUploadAssetURL(init); assetURL != "" {
+		out["asset_url"] = assetURL
+	}
+	if name := initUploadName(init); name != "" {
+		out["name"] = name
+	}
+	if _, ok := init["upload_data"]; ok {
+		out["upload_credentials_available_with_raw"] = true
+	}
+	return out
+}
+
+func initUploadAssetID(init map[string]any) string {
+	for _, key := range []string{"id", "asset_id"} {
+		if value, ok := init[key].(string); ok && value != "" {
+			return value
+		}
+	}
+	if attachment, ok := init["attachment"].(map[string]any); ok {
+		for _, key := range []string{"id", "asset_id"} {
+			if value, ok := attachment[key].(string); ok && value != "" {
+				return value
+			}
+		}
+	}
+	return ""
+}
+
+func initUploadAssetURL(init map[string]any) string {
+	for _, key := range []string{"asset_url", "asset"} {
+		if value, ok := init[key].(string); ok && value != "" {
+			return value
+		}
+	}
+	if attachment, ok := init["attachment"].(map[string]any); ok {
+		for _, key := range []string{"asset_url", "asset"} {
+			if value, ok := attachment[key].(string); ok && value != "" {
+				return value
+			}
+		}
+		if attrs, ok := attachment["attributes"].(map[string]any); ok {
+			if value, ok := attrs["url"].(string); ok && value != "" {
+				return value
+			}
+		}
+	}
+	if attrs, ok := init["attributes"].(map[string]any); ok {
+		if value, ok := attrs["url"].(string); ok && value != "" {
+			return value
+		}
+	}
+	return ""
+}
+
+func initUploadName(init map[string]any) string {
+	if value, ok := init["name"].(string); ok && value != "" {
+		return value
+	}
+	if attachment, ok := init["attachment"].(map[string]any); ok {
+		if value, ok := attachment["name"].(string); ok && value != "" {
+			return value
+		}
+		if attrs, ok := attachment["attributes"].(map[string]any); ok {
+			if value, ok := attrs["name"].(string); ok && value != "" {
+				return value
+			}
+		}
+	}
+	if attrs, ok := init["attributes"].(map[string]any); ok {
+		if value, ok := attrs["name"].(string); ok && value != "" {
+			return value
+		}
+	}
+	return ""
+}
+
 func attachmentURL(att plane.Attachment, fallback string) string {
 	if attrs, ok := att["attributes"].(map[string]any); ok {
 		if u, ok := attrs["url"].(string); ok && isDownloadableAttachmentURL(u) {