feat(mcp): parse query string as mcp client options in mcp server

Author: stainless-app[bot]

packages/mcp-server/README.md

@@ -152,6 +152,19 @@ A configuration JSON for this server might look like this, assuming the server i
 }
 ```
 
+The command-line arguments for filtering tools and specifying clients can also be used as query parameters in the URL.
+For example, to exclude specific tools while including others, use the URL:
+
+```
+http://localhost:3000?resource=cards&resource=accounts&no_tool=create_cards
+```
+
+Or, to configure for the Cursor client, with a custom max tool name length, use the URL:
+
+```
+http://localhost:3000?client=cursor&capability=tool-name-length%3D40
+```
+
 ## Importing the tools and server individually
 
 ```js

packages/mcp-server/package.json

@@ -28,20 +28,22 @@
   },
   "dependencies": {
     "isaacus": "file:../../dist/",
+    "@cloudflare/cabidela": "^0.2.4",
     "@modelcontextprotocol/sdk": "^1.11.5",
     "express": "^5.1.0",
     "jq-web": "https://github.com/stainless-api/jq-web/releases/download/v0.8.6/jq-web.tar.gz",
+    "qs": "^6.14.0",
     "yargs": "^17.7.2",
-    "@cloudflare/cabidela": "^0.2.4",
     "zod": "^3.25.20",
-    "zod-to-json-schema": "^3.24.5"
+    "zod-to-json-schema": "^3.24.5",
+    "zod-validation-error": "^4.0.1"
   },
   "bin": {
     "mcp-server": "dist/index.js"
   },
   "devDependencies": {
-    "@types/jest": "^29.4.0",
     "@types/express": "^5.0.3",
+    "@types/jest": "^29.4.0",
     "@types/yargs": "^17.0.8",
     "@typescript-eslint/eslint-plugin": "8.31.1",
     "@typescript-eslint/parser": "8.31.1",

packages/mcp-server/src/compat.ts

@@ -1,4 +1,5 @@
 import { Tool } from '@modelcontextprotocol/sdk/types.js';
+import { z } from 'zod';
 import { Endpoint } from './tools';
 
 export interface ClientCapabilities {
@@ -19,7 +20,8 @@ export const defaultClientCapabilities: ClientCapabilities = {
   toolNameLength: undefined,
 };
 
-export type ClientType = 'openai-agents' | 'claude' | 'claude-code' | 'cursor';
+export const ClientType = z.enum(['openai-agents', 'claude', 'claude-code', 'cursor']);
+export type ClientType = z.infer<typeof ClientType>;
 
 // Client presets for compatibility
 // Note that these could change over time as models get better, so this is

packages/mcp-server/src/http.ts

@@ -4,13 +4,33 @@ import { McpServer } from '@modelcontextprotocol/sdk/server/mcp';
 import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/streamableHttp.js';
 
 import express from 'express';
-import { McpOptions } from './options';
+import { fromError } from 'zod-validation-error/v3';
+import { McpOptions, parseQueryOptions } from './options';
 import { initMcpServer, newMcpServer } from './server';
 import { parseAuthHeaders } from './headers';
 import { Endpoint } from './tools';
 
-const newServer = (mcpOptions: McpOptions, req: express.Request, res: express.Response): McpServer | null => {
+const newServer = (
+  defaultMcpOptions: McpOptions,
+  req: express.Request,
+  res: express.Response,
+): McpServer | null => {
   const server = newMcpServer();
+
+  let mcpOptions: McpOptions;
+  try {
+    mcpOptions = parseQueryOptions(defaultMcpOptions, req.query);
+  } catch (error) {
+    res.status(400).json({
+      jsonrpc: '2.0',
+      error: {
+        code: -32000,
+        message: `Invalid request: ${fromError(error)}`,
+      },
+    });
+    return null;
+  }
+
   try {
     const authOptions = parseAuthHeaders(req);
     initMcpServer({
@@ -71,6 +91,7 @@ const del = async (req: express.Request, res: express.Response) => {
 
 export const streamableHTTPApp = (options: McpOptions): express.Express => {
   const app = express();
+  app.set('query parser', 'extended');
   app.use(express.json());
 
   app.get('/', get);

packages/mcp-server/src/index.ts

@@ -2,7 +2,7 @@
 
 import { selectTools } from './server';
 import { Endpoint, endpoints } from './tools';
-import { McpOptions, parseOptions } from './options';
+import { McpOptions, parseCLIOptions } from './options';
 import { launchStdioServer } from './stdio';
 import { launchStreamableHTTPServer } from './http';
 
@@ -40,7 +40,7 @@ if (require.main === module) {
 
 function parseOptionsOrError() {
   try {
-    return parseOptions();
+    return parseCLIOptions();
   } catch (error) {
     console.error('Error parsing options:', error);
     process.exit(1);

packages/mcp-server/src/options.ts

@@ -1,5 +1,7 @@
+import qs from 'qs';
 import yargs from 'yargs';
 import { hideBin } from 'yargs/helpers';
+import z from 'zod';
 import { endpoints, Filter } from './tools';
 import { ClientCapabilities, knownClients, ClientType } from './compat';
 
@@ -47,7 +49,7 @@ function parseCapabilityValue(cap: string): { name: Capability; value?: number }
   return { name: cap as Capability };
 }
 
-export function parseOptions(): CLIOptions {
+export function parseCLIOptions(): CLIOptions {
   const opts = yargs(hideBin(process.argv))
     .option('tools', {
       type: 'string',
@@ -271,6 +273,123 @@ export function parseOptions(): CLIOptions {
   };
 }
 
+const coerceArray = <T extends z.ZodTypeAny>(zodType: T) =>
+  z.preprocess(
+    (val) =>
+      Array.isArray(val) ? val
+      : val ? [val]
+      : val,
+    z.array(zodType).optional(),
+  );
+
+const QueryOptions = z.object({
+  tools: coerceArray(z.enum(['dynamic', 'all'])).describe('Use dynamic tools or all tools'),
+  no_tools: coerceArray(z.enum(['dynamic', 'all'])).describe('Do not use dynamic tools or all tools'),
+  tool: coerceArray(z.string()).describe('Include tools matching the specified names'),
+  resource: coerceArray(z.string()).describe('Include tools matching the specified resources'),
+  operation: coerceArray(z.enum(['read', 'write'])).describe(
+    'Include tools matching the specified operations',
+  ),
+  tag: coerceArray(z.string()).describe('Include tools with the specified tags'),
+  no_tool: coerceArray(z.string()).describe('Exclude tools matching the specified names'),
+  no_resource: coerceArray(z.string()).describe('Exclude tools matching the specified resources'),
+  no_operation: coerceArray(z.enum(['read', 'write'])).describe(
+    'Exclude tools matching the specified operations',
+  ),
+  no_tag: coerceArray(z.string()).describe('Exclude tools with the specified tags'),
+  client: ClientType.optional().describe('Specify the MCP client being used'),
+  capability: coerceArray(z.string()).describe('Specify client capabilities'),
+  no_capability: coerceArray(z.enum(CAPABILITY_CHOICES)).describe('Unset client capabilities'),
+});
+
+export function parseQueryOptions(defaultOptions: McpOptions, query: unknown): McpOptions {
+  const queryObject = typeof query === 'string' ? qs.parse(query) : query;
+  const queryOptions = QueryOptions.parse(queryObject);
+
+  const filters: Filter[] = [...defaultOptions.filters];
+
+  for (const resource of queryOptions.resource || []) {
+    filters.push({ type: 'resource', op: 'include', value: resource });
+  }
+  for (const operation of queryOptions.operation || []) {
+    filters.push({ type: 'operation', op: 'include', value: operation });
+  }
+  for (const tag of queryOptions.tag || []) {
+    filters.push({ type: 'tag', op: 'include', value: tag });
+  }
+  for (const tool of queryOptions.tool || []) {
+    filters.push({ type: 'tool', op: 'include', value: tool });
+  }
+  for (const resource of queryOptions.no_resource || []) {
+    filters.push({ type: 'resource', op: 'exclude', value: resource });
+  }
+  for (const operation of queryOptions.no_operation || []) {
+    filters.push({ type: 'operation', op: 'exclude', value: operation });
+  }
+  for (const tag of queryOptions.no_tag || []) {
+    filters.push({ type: 'tag', op: 'exclude', value: tag });
+  }
+  for (const tool of queryOptions.no_tool || []) {
+    filters.push({ type: 'tool', op: 'exclude', value: tool });
+  }
+
+  // Parse client capabilities
+  const clientCapabilities: ClientCapabilities = {
+    topLevelUnions: true,
+    validJson: true,
+    refs: true,
+    unions: true,
+    formats: true,
+    toolNameLength: undefined,
+    ...defaultOptions.capabilities,
+  };
+
+  for (const cap of queryOptions.capability || []) {
+    const parsed = parseCapabilityValue(cap);
+    if (parsed.name === 'top-level-unions') {
+      clientCapabilities.topLevelUnions = true;
+    } else if (parsed.name === 'valid-json') {
+      clientCapabilities.validJson = true;
+    } else if (parsed.name === 'refs') {
+      clientCapabilities.refs = true;
+    } else if (parsed.name === 'unions') {
+      clientCapabilities.unions = true;
+    } else if (parsed.name === 'formats') {
+      clientCapabilities.formats = true;
+    } else if (parsed.name === 'tool-name-length') {
+      clientCapabilities.toolNameLength = parsed.value;
+    }
+  }
+
+  for (const cap of queryOptions.no_capability || []) {
+    if (cap === 'top-level-unions') {
+      clientCapabilities.topLevelUnions = false;
+    } else if (cap === 'valid-json') {
+      clientCapabilities.validJson = false;
+    } else if (cap === 'refs') {
+      clientCapabilities.refs = false;
+    } else if (cap === 'unions') {
+      clientCapabilities.unions = false;
+    } else if (cap === 'formats') {
+      clientCapabilities.formats = false;
+    } else if (cap === 'tool-name-length') {
+      clientCapabilities.toolNameLength = undefined;
+    }
+  }
+
+  return {
+    client: queryOptions.client ?? defaultOptions.client,
+    includeDynamicTools:
+      defaultOptions.includeDynamicTools ??
+      (queryOptions.tools?.includes('dynamic') && !queryOptions.no_tools?.includes('dynamic')),
+    includeAllTools:
+      defaultOptions.includeAllTools ??
+      (queryOptions.tools?.includes('all') && !queryOptions.no_tools?.includes('all')),
+    filters,
+    capabilities: clientCapabilities,
+  };
+}
+
 function getCapabilitiesExplanation(): string {
   return `
 Client Capabilities Explanation: