feat(core): Add recordInputs/recordOutputs options to MCP server wrapper

packages/core/src/integrations/mcp-server/attributeExtraction.ts

@@ -95,12 +95,14 @@ export function getNotificationAttributes(
  * @param type - Span type (request or notification)
  * @param message - JSON-RPC message
  * @param params - Optional parameters for attribute extraction
+ * @param recordInputs - Whether to capture input arguments in spans
  * @returns Type-specific attributes for span instrumentation
  */
 export function buildTypeSpecificAttributes(
   type: McpSpanType,
   message: JsonRpcRequest | JsonRpcNotification,
   params?: Record<string, unknown>,
+  recordInputs?: boolean,
 ): Record<string, string | number> {
   if (type === 'request') {
     const request = message as JsonRpcRequest;
@@ -109,7 +111,7 @@ export function buildTypeSpecificAttributes(
     return {
       ...(request.id !== undefined && { [MCP_REQUEST_ID_ATTRIBUTE]: String(request.id) }),
       ...targetInfo.attributes,
-      ...getRequestArguments(request.method, params || {}),
+      ...(recordInputs ? getRequestArguments(request.method, params || {}) : {}),
     };
   }
 

packages/core/src/integrations/mcp-server/correlation.ts

@@ -6,14 +6,12 @@
  * request ID collisions between different MCP sessions.
  */
 
-import { getClient } from '../../currentScopes';
 import { SPAN_STATUS_ERROR } from '../../tracing';
 import type { Span } from '../../types-hoist/span';
 import { MCP_PROTOCOL_VERSION_ATTRIBUTE } from './attributes';
-import { filterMcpPiiFromSpanData } from './piiFiltering';
 import { extractPromptResultAttributes, extractToolResultAttributes } from './resultExtraction';
 import { buildServerAttributesFromInfo, extractSessionDataFromInitializeResponse } from './sessionExtraction';
-import type { MCPTransport, RequestId, RequestSpanMapValue } from './types';
+import type { MCPTransport, RequestId, RequestSpanMapValue, ResolvedMcpOptions } from './types';
 
 /**
  * Transport-scoped correlation system that prevents collisions between different MCP sessions
@@ -57,8 +55,14 @@ export function storeSpanForRequest(transport: MCPTransport, requestId: RequestI
  * @param transport - MCP transport instance
  * @param requestId - Request identifier
  * @param result - Execution result for attribute extraction
+ * @param options - Resolved MCP options
  */
-export function completeSpanWithResults(transport: MCPTransport, requestId: RequestId, result: unknown): void {
+export function completeSpanWithResults(
+  transport: MCPTransport,
+  requestId: RequestId,
+  result: unknown,
+  options: ResolvedMcpOptions,
+): void {
   const spanMap = getOrCreateSpanMap(transport);
   const spanData = spanMap.get(requestId);
   if (spanData) {
@@ -77,18 +81,10 @@ export function completeSpanWithResults(transport: MCPTransport, requestId: Requ
 
       span.setAttributes(initAttributes);
     } else if (method === 'tools/call') {
-      const rawToolAttributes = extractToolResultAttributes(result);
-      const client = getClient();
-      const sendDefaultPii = Boolean(client?.getOptions().sendDefaultPii);
-      const toolAttributes = filterMcpPiiFromSpanData(rawToolAttributes, sendDefaultPii);
-
+      const toolAttributes = extractToolResultAttributes(result, options.recordOutputs);
       span.setAttributes(toolAttributes);
     } else if (method === 'prompts/get') {
-      const rawPromptAttributes = extractPromptResultAttributes(result);
-      const client = getClient();
-      const sendDefaultPii = Boolean(client?.getOptions().sendDefaultPii);
-      const promptAttributes = filterMcpPiiFromSpanData(rawPromptAttributes, sendDefaultPii);
-
+      const promptAttributes = extractPromptResultAttributes(result, options.recordOutputs);
       span.setAttributes(promptAttributes);
     }
 

packages/core/src/integrations/mcp-server/index.ts

@@ -1,7 +1,8 @@
+import { getClient } from '../../currentScopes';
 import { fill } from '../../utils/object';
 import { wrapAllMCPHandlers } from './handlers';
 import { wrapTransportError, wrapTransportOnClose, wrapTransportOnMessage, wrapTransportSend } from './transport';
-import type { MCPServerInstance, MCPTransport } from './types';
+import type { MCPServerInstance, McpServerWrapperOptions, MCPTransport, ResolvedMcpOptions } from './types';
 import { validateMcpServerInstance } from './validation';
 
 /**
@@ -22,18 +23,26 @@ const wrappedMcpServerInstances = new WeakSet();
  * import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
  * import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/streamableHttp.js';
  *
+ * // Default: inputs/outputs captured based on sendDefaultPii option
  * const server = Sentry.wrapMcpServerWithSentry(
  *   new McpServer({ name: "my-server", version: "1.0.0" })
  * );
  *
+ * // Explicitly control input/output capture
+ * const server = Sentry.wrapMcpServerWithSentry(
+ *   new McpServer({ name: "my-server", version: "1.0.0" }),
+ *   { recordInputs: true, recordOutputs: false }
+ * );
+ *
  * const transport = new StreamableHTTPServerTransport();
  * await server.connect(transport);
  * ```
  *
  * @param mcpServerInstance - MCP server instance to instrument
+ * @param options - Optional configuration for recording inputs and outputs
  * @returns Instrumented server instance (same reference)
  */
-export function wrapMcpServerWithSentry<S extends object>(mcpServerInstance: S): S {
+export function wrapMcpServerWithSentry<S extends object>(mcpServerInstance: S, options?: McpServerWrapperOptions): S {
   if (wrappedMcpServerInstances.has(mcpServerInstance)) {
     return mcpServerInstance;
   }
@@ -43,6 +52,13 @@ export function wrapMcpServerWithSentry<S extends object>(mcpServerInstance: S):
   }
 
   const serverInstance = mcpServerInstance as MCPServerInstance;
+  const client = getClient();
+  const sendDefaultPii = Boolean(client?.getOptions().sendDefaultPii);
+
+  const resolvedOptions: ResolvedMcpOptions = {
+    recordInputs: options?.recordInputs ?? sendDefaultPii,
+    recordOutputs: options?.recordOutputs ?? sendDefaultPii,
+  };
 
   fill(serverInstance, 'connect', originalConnect => {
     return async function (this: MCPServerInstance, transport: MCPTransport, ...restArgs: unknown[]) {
@@ -52,8 +68,8 @@ export function wrapMcpServerWithSentry<S extends object>(mcpServerInstance: S):
         ...restArgs,
       );
 
-      wrapTransportOnMessage(transport);
-      wrapTransportSend(transport);
+      wrapTransportOnMessage(transport, resolvedOptions);
+      wrapTransportSend(transport, resolvedOptions);
       wrapTransportOnClose(transport);
       wrapTransportError(transport);
 

packages/core/src/integrations/mcp-server/piiFiltering.ts

@@ -1,71 +1,37 @@
 /**
  * PII filtering for MCP server spans
  *
- * Removes sensitive data when sendDefaultPii is false.
- * Uses configurable attribute filtering to protect user privacy.
+ * Removes network-level sensitive data when sendDefaultPii is false.
+ * Input/output data (request arguments, tool/prompt results) is controlled
+ * separately via recordInputs/recordOutputs options.
  */
 import type { SpanAttributeValue } from '../../types-hoist/span';
-import {
-  CLIENT_ADDRESS_ATTRIBUTE,
-  CLIENT_PORT_ATTRIBUTE,
-  MCP_LOGGING_MESSAGE_ATTRIBUTE,
-  MCP_PROMPT_RESULT_DESCRIPTION_ATTRIBUTE,
-  MCP_PROMPT_RESULT_MESSAGE_CONTENT_ATTRIBUTE,
-  MCP_PROMPT_RESULT_PREFIX,
-  MCP_REQUEST_ARGUMENT,
-  MCP_RESOURCE_URI_ATTRIBUTE,
-  MCP_TOOL_RESULT_CONTENT_ATTRIBUTE,
-  MCP_TOOL_RESULT_PREFIX,
-} from './attributes';
+import { CLIENT_ADDRESS_ATTRIBUTE, CLIENT_PORT_ATTRIBUTE, MCP_RESOURCE_URI_ATTRIBUTE } from './attributes';
 
 /**
- * PII attributes that should be removed when sendDefaultPii is false
+ * Network PII attributes that should be removed when sendDefaultPii is false
  * @internal
  */
-const PII_ATTRIBUTES = new Set([
-  CLIENT_ADDRESS_ATTRIBUTE,
-  CLIENT_PORT_ATTRIBUTE,
-  MCP_LOGGING_MESSAGE_ATTRIBUTE,
-  MCP_PROMPT_RESULT_DESCRIPTION_ATTRIBUTE,
-  MCP_PROMPT_RESULT_MESSAGE_CONTENT_ATTRIBUTE,
-  MCP_RESOURCE_URI_ATTRIBUTE,
-  MCP_TOOL_RESULT_CONTENT_ATTRIBUTE,
-]);
+const NETWORK_PII_ATTRIBUTES = new Set([CLIENT_ADDRESS_ATTRIBUTE, CLIENT_PORT_ATTRIBUTE, MCP_RESOURCE_URI_ATTRIBUTE]);
 
 /**
- * Checks if an attribute key should be considered PII.
+ * Checks if an attribute key should be considered network PII.
  *
  * Returns true for:
- * - Explicit PII attributes (client.address, client.port, mcp.logging.message, etc.)
- * - All request arguments (mcp.request.argument.*)
- * - Tool and prompt result content (mcp.tool.result.*, mcp.prompt.result.*) except metadata
- *
- * Preserves metadata attributes ending with _count, _error, or .is_error as they don't contain sensitive data.
+ * - client.address (IP address)
+ * - client.port (port number)
+ * - mcp.resource.uri (potentially sensitive URIs)
  *
  * @param key - Attribute key to evaluate
- * @returns true if the attribute should be filtered out (is PII), false if it should be preserved
+ * @returns true if the attribute should be filtered out (is network PII), false if it should be preserved
  * @internal
  */
-function isPiiAttribute(key: string): boolean {
-  if (PII_ATTRIBUTES.has(key)) {
-    return true;
-  }
-
-  if (key.startsWith(`${MCP_REQUEST_ARGUMENT}.`)) {
-    return true;
-  }
-
-  if (key.startsWith(`${MCP_TOOL_RESULT_PREFIX}.`) || key.startsWith(`${MCP_PROMPT_RESULT_PREFIX}.`)) {
-    if (!key.endsWith('_count') && !key.endsWith('_error') && !key.endsWith('.is_error')) {
-      return true;
-    }
-  }
-
-  return false;
+function isNetworkPiiAttribute(key: string): boolean {
+  return NETWORK_PII_ATTRIBUTES.has(key);
 }
 
 /**
- * Removes PII attributes from span data when sendDefaultPii is false
+ * Removes network PII attributes from span data when sendDefaultPii is false
  * @param spanData - Raw span attributes
  * @param sendDefaultPii - Whether to include PII data
  * @returns Filtered span attributes
@@ -80,7 +46,7 @@ export function filterMcpPiiFromSpanData(
 
   return Object.entries(spanData).reduce(
     (acc, [key, value]) => {
-      if (!isPiiAttribute(key)) {
+      if (!isNetworkPiiAttribute(key)) {
         acc[key] = value as SpanAttributeValue;
       }
       return acc;

packages/core/src/integrations/mcp-server/resultExtraction.ts

@@ -15,9 +15,13 @@ import { isValidContentItem } from './validation';
 /**
  * Build attributes for tool result content items
  * @param content - Array of content items from tool result
- * @returns Attributes extracted from each content item including type, text, mime type, URI, and resource info
+ * @param includeContent - Whether to include actual content (text, URIs) or just metadata
+ * @returns Attributes extracted from each content item
  */
-function buildAllContentItemAttributes(content: unknown[]): Record<string, string | number | boolean> {
+function buildAllContentItemAttributes(
+  content: unknown[],
+  includeContent: boolean,
+): Record<string, string | number | boolean> {
   const attributes: Record<string, string | number> = {
     [MCP_TOOL_RESULT_CONTENT_COUNT_ATTRIBUTE]: content.length,
   };
@@ -29,29 +33,34 @@ function buildAllContentItemAttributes(content: unknown[]): Record<string, strin
 
     const prefix = content.length === 1 ? 'mcp.tool.result' : `mcp.tool.result.${i}`;
 
-    const safeSet = (key: string, value: unknown): void => {
-      if (typeof value === 'string') {
-        attributes[`${prefix}.${key}`] = value;
-      }
-    };
+    if (typeof item.type === 'string') {
+      attributes[`${prefix}.content_type`] = item.type;
+    }
 
-    safeSet('content_type', item.type);
-    safeSet('mime_type', item.mimeType);
-    safeSet('uri', item.uri);
-    safeSet('name', item.name);
+    if (includeContent) {
+      const safeSet = (key: string, value: unknown): void => {
+        if (typeof value === 'string') {
+          attributes[`${prefix}.${key}`] = value;
+        }
+      };
 
-    if (typeof item.text === 'string') {
-      attributes[`${prefix}.content`] = item.text;
-    }
+      safeSet('mime_type', item.mimeType);
+      safeSet('uri', item.uri);
+      safeSet('name', item.name);
 
-    if (typeof item.data === 'string') {
-      attributes[`${prefix}.data_size`] = item.data.length;
-    }
+      if (typeof item.text === 'string') {
+        attributes[`${prefix}.content`] = item.text;
+      }
 
-    const resource = item.resource;
-    if (isValidContentItem(resource)) {
-      safeSet('resource_uri', resource.uri);
-      safeSet('resource_mime_type', resource.mimeType);
+      if (typeof item.data === 'string') {
+        attributes[`${prefix}.data_size`] = item.data.length;
+      }
+
+      const resource = item.resource;
+      if (isValidContentItem(resource)) {
+        safeSet('resource_uri', resource.uri);
+        safeSet('resource_mime_type', resource.mimeType);
+      }
     }
   }
 
@@ -61,14 +70,18 @@ function buildAllContentItemAttributes(content: unknown[]): Record<string, strin
 /**
  * Extract tool result attributes for span instrumentation
  * @param result - Tool execution result
+ * @param recordOutputs - Whether to include actual content or just metadata (counts, error status)
  * @returns Attributes extracted from tool result content
  */
-export function extractToolResultAttributes(result: unknown): Record<string, string | number | boolean> {
+export function extractToolResultAttributes(
+  result: unknown,
+  recordOutputs: boolean,
+): Record<string, string | number | boolean> {
   if (!isValidContentItem(result)) {
     return {};
   }
 
-  const attributes = Array.isArray(result.content) ? buildAllContentItemAttributes(result.content) : {};
+  const attributes = Array.isArray(result.content) ? buildAllContentItemAttributes(result.content, recordOutputs) : {};
 
   if (typeof result.isError === 'boolean') {
     attributes[MCP_TOOL_RESULT_IS_ERROR_ATTRIBUTE] = result.isError;
@@ -80,43 +93,49 @@ export function extractToolResultAttributes(result: unknown): Record<string, str
 /**
  * Extract prompt result attributes for span instrumentation
  * @param result - Prompt execution result
+ * @param recordOutputs - Whether to include actual content or just metadata (counts)
  * @returns Attributes extracted from prompt result
  */
-export function extractPromptResultAttributes(result: unknown): Record<string, string | number | boolean> {
+export function extractPromptResultAttributes(
+  result: unknown,
+  recordOutputs: boolean,
+): Record<string, string | number | boolean> {
   const attributes: Record<string, string | number | boolean> = {};
   if (!isValidContentItem(result)) {
     return attributes;
   }
 
-  if (typeof result.description === 'string') {
+  if (recordOutputs && typeof result.description === 'string') {
     attributes[MCP_PROMPT_RESULT_DESCRIPTION_ATTRIBUTE] = result.description;
   }
 
   if (Array.isArray(result.messages)) {
     attributes[MCP_PROMPT_RESULT_MESSAGE_COUNT_ATTRIBUTE] = result.messages.length;
 
-    const messages = result.messages;
-    for (const [i, message] of messages.entries()) {
-      if (!isValidContentItem(message)) {
-        continue;
-      }
+    if (recordOutputs) {
+      const messages = result.messages;
+      for (const [i, message] of messages.entries()) {
+        if (!isValidContentItem(message)) {
+          continue;
+        }
 
-      const prefix = messages.length === 1 ? 'mcp.prompt.result' : `mcp.prompt.result.${i}`;
+        const prefix = messages.length === 1 ? 'mcp.prompt.result' : `mcp.prompt.result.${i}`;
 
-      const safeSet = (key: string, value: unknown): void => {
-        if (typeof value === 'string') {
-          const attrName = messages.length === 1 ? `${prefix}.message_${key}` : `${prefix}.${key}`;
-          attributes[attrName] = value;
-        }
-      };
+        const safeSet = (key: string, value: unknown): void => {
+          if (typeof value === 'string') {
+            const attrName = messages.length === 1 ? `${prefix}.message_${key}` : `${prefix}.${key}`;
+            attributes[attrName] = value;
+          }
+        };
 
-      safeSet('role', message.role);
+        safeSet('role', message.role);
 
-      if (isValidContentItem(message.content)) {
-        const content = message.content;
-        if (typeof content.text === 'string') {
-          const attrName = messages.length === 1 ? `${prefix}.message_content` : `${prefix}.content`;
-          attributes[attrName] = content.text;
+        if (isValidContentItem(message.content)) {
+          const content = message.content;
+          if (typeof content.text === 'string') {
+            const attrName = messages.length === 1 ? `${prefix}.message_content` : `${prefix}.content`;
+            attributes[attrName] = content.text;
+          }
         }
       }
     }