Repository navigation
Need to override json limit defaults for express body parser in createMcpExpressApp() #1354
Description
Hi! 👋
Firstly, thanks for your work on this project! 🙂
Today I used patch-package to patch @modelcontextprotocol/[email protected] for the project I'm working on.
The createMcpExpressApp() use the json bodyparser with default limit of 100kb because it is not possible to pass a limit size as option.
Here is the diff that solved my problem:
diff --git a/node_modules/@modelcontextprotocol/sdk/dist/esm/server/express.d.ts b/node_modules/@modelcontextprotocol/sdk/dist/esm/server/express.d.ts
index 7746e82..824b80f 100644
--- a/node_modules/@modelcontextprotocol/sdk/dist/esm/server/express.d.ts
+++ b/node_modules/@modelcontextprotocol/sdk/dist/esm/server/express.d.ts
@@ -17,6 +17,8 @@ export interface CreateMcpExpressAppOptions {
* to restrict which hostnames are allowed.
*/
allowedHosts?: string[];
+ /** Controls the maximum request body size. */
+ limit?: string;
}
/**
* Creates an Express application pre-configured for MCP servers.
diff --git a/node_modules/@modelcontextprotocol/sdk/dist/esm/server/express.js b/node_modules/@modelcontextprotocol/sdk/dist/esm/server/express.js
index a23a57b..0ad4703 100644
--- a/node_modules/@modelcontextprotocol/sdk/dist/esm/server/express.js
+++ b/node_modules/@modelcontextprotocol/sdk/dist/esm/server/express.js
@@ -24,9 +24,9 @@ import { hostHeaderValidation, localhostHostValidation } from './middleware/host
* ```
*/
export function createMcpExpressApp(options = {}) {
- const { host = '127.0.0.1', allowedHosts } = options;
+ const { host = '127.0.0.1', allowedHosts, limit } = options;
const app = express();
- app.use(express.json());
+ limit ? app.use(express.json({ limit })) : app.use(express.json());
// If allowedHosts is explicitly provided, use that for validation
if (allowedHosts) {
app.use(hostHeaderValidation(allowedHosts));This issue body was partially generated by patch-package.
Activity
[-]Override json limit defaults in express body parser in createMcpExpressApp()[/-][+]Need a way to override json limit defaults for express body parser in createMcpExpressApp()[/+][-]Need a way to override json limit defaults for express body parser in createMcpExpressApp()[/-][+]Need to override json limit defaults for express body parser in createMcpExpressApp()[/+]fix: patch json body parser limit
feat(express): add jsonBodyLimit option to createMcpExpressApp
Rootlogger commentedon Mar 3, 2026
I'd like to work on this. Please assign it to me.
fix(server): add limit option for express json body parser
feat(express): add jsonOptions to createMcpExpressApp()
Add jsonLimit option to createMcpExpressApp