Add header to MCP server to expand authentication capabilities

src/client/index.ts

@@ -407,9 +407,10 @@ export class Client<
       | typeof CallToolResultSchema
       | typeof CompatibilityCallToolResultSchema = CallToolResultSchema,
     options?: RequestOptions,
+    headers?: Record<string, string | boolean | number>
   ) {
     return this.request(
-      { method: "tools/call", params },
+      { method: "tools/call", params, headers },
       resultSchema,
       options,
     );

src/server/mcp.ts

@@ -143,7 +143,7 @@ export class McpServer {
           const args = parseResult.data;
           const cb = tool.callback as ToolCallback<ZodRawShape>;
           try {
-            return await Promise.resolve(cb(args, extra));
+            return await Promise.resolve(cb(args, extra, request.headers));
           } catch (error) {
             return {
               content: [
@@ -158,7 +158,7 @@ export class McpServer {
         } else {
           const cb = tool.callback as ToolCallback<undefined>;
           try {
-            return await Promise.resolve(cb(extra));
+            return await Promise.resolve(cb(extra, request.headers));
           } catch (error) {
             return {
               content: [
@@ -695,8 +695,9 @@ export type ToolCallback<Args extends undefined | ZodRawShape = undefined> =
     ? (
         args: z.objectOutputType<Args, ZodTypeAny>,
         extra: RequestHandlerExtra,
+        headers: Record<string, string | number | boolean> | undefined
       ) => CallToolResult | Promise<CallToolResult>
-    : (extra: RequestHandlerExtra) => CallToolResult | Promise<CallToolResult>;
+    : (extra: RequestHandlerExtra, headers: Record<string, string | number | boolean> | undefined) => CallToolResult | Promise<CallToolResult>;
 
 type RegisteredTool = {
   description?: string;

src/types.ts

@@ -36,6 +36,7 @@ const BaseRequestParamsSchema = z
 
 export const RequestSchema = z.object({
   method: z.string(),
+  headers: z.optional(z.record(z.union([z.string(), z.number(), z.boolean()]))),
   params: z.optional(BaseRequestParamsSchema),
 });