Enterprise Search
BM25 progressive tool discovery for large tool catalogs
The Enterprise Search template (TypeScript only) shows how to serve a large tool catalog without flooding the model's context. Tools are grouped by domain with @Controller, and BM25SearchTransform collapses the catalog into two meta-tools that the model uses to find and call the tool it needs.
What's included
Three controllers
Finance, inventory, and support tools, each with a name prefix.
BM25 search
In-memory search over tool names, descriptions, and parameters.
Always-visible tools
Four bootstrap tools stay in the catalog.
Widgets
financial-summary, inventory-monitor, and system-health.
Create the project
Scaffold the template and start it:
npx @nitrostack/cli init enterprise-tools --template typescript-enterprise-search
cd enterprise-tools
npm run devHow it works
Each controller adds a prefix to its tools, so calculate_tax in @Controller('finance') is exposed as finance_calculate_tax:
@Controller('finance')
export class FinanceController {
@Tool({
name: 'calculate_tax',
description: 'Calculate sales and corporate tax for a transaction',
inputSchema: z.object({
amount: z.number().positive().describe('Gross transaction amount'),
region: z.enum(['US-CA', 'US-NY', 'EU-DE', 'UK']).describe('Tax jurisdiction'),
}),
})
async calculateTax(input: { amount: number; region: string }, ctx: ExecutionContext) {
// ...
}
}The root module attaches the transform and lists the tools that should stay visible:
@McpApp({
module: AppModule,
server: { name: 'enterprise-search-service', version: '1.0.0' },
transforms: [
new BM25SearchTransform({
defaultLimit: 5,
alwaysVisible: [
'support_auth_login',
'support_get_system_status',
'finance_get_financial_summary',
'inventory_report',
],
}),
],
})What the model sees
tools/list returns six tools instead of the full catalog: search_tools, call_tool, and the four always-visible tools. To use anything else, the model first searches, then calls the tool through call_tool:
{ "name": "search_tools", "arguments": { "query": "calculate customer sales tax" } }{ "name": "call_tool", "arguments": { "name": "finance_calculate_tax", "arguments": { "amount": 1000, "region": "US-CA" } } }The second call returns { "gross": 1000, "tax": 82.5, "net": 1082.5 }. Arguments are validated against the tool's schema even when it is called through call_tool.