MCP server

Nordlet serves the Model Context Protocol at https://api.nordlet.com/mcp. An AI assistant connected to it can search the API, read the request schema of any operation and call it, with the same API key, company and scopes as a direct request. Every tool call is an ordinary API request: it is authenticated, rate limited and metered like one, and a mutating call changes the company's books.

Connect

The endpoint speaks Streamable HTTP and is authenticated with the Bearer API key from Getting started. In Claude Code:

claude mcp add --transport http nordlet https://api.nordlet.com/mcp --header "Authorization: Bearer nl_..."

Any other MCP client takes the same URL and header. A key scoped to *:read can call only the read operations; the tools report a missing scope as the API's 403 error.

Tools

Three tools cover every operation of the API:

Tool	What it does
search_operations	Finds operations by words in their name, path, summary or description, optionally within one module (sales, bank, reports, ...). Without a query it lists the modules.
describe_operation	Returns the method, path, description and JSON request schema of one operation; includeResponse: true adds the schema of the 200 response.
call_operation	Runs one operation with a JSON body. The response body comes back as JSON; a 4xx or 5xx answer comes back as a tool error with the status and the error envelope. An optional idempotencyKey is sent as the Idempotency-Key header, so a repeated call with the same key replays the first answer instead of repeating the effect.

The most used operations are also direct tools with their own request schemas, so an assistant sees their fields without a lookup: partners_list, partners_get, partners_create, partners_find_or_create, catalog_items_list, sales_invoices_list, sales_invoices_get, sales_invoices_create, sales_invoices_issue, sales_invoices_send, purchases_invoices_list, purchases_invoices_create, purchases_invoices_register, bank_transactions_list, bank_transactions_import, bank_transactions_match, ledger_journal_transactions_list, reports_trial_balance, reports_financial_statements, reports_vat_summary and reports_debt_aging. Each tool carries the MCP annotations (readOnlyHint, destructiveHint) that tell the client whether it writes.

The operation index and the schemas are generated from the same OpenAPI description as the API reference and the SDKs, so an operation added to the API appears in search_operations with the release that adds it. The server's instructions remind the assistant of the conventions: amounts are decimal strings, lists take page, pageSize, sort and filter, and a country filing answers 422 for a company outside that country.