Codat vs QuickBooks Online API + MCP

Codat

Public OpenAPI specs, an Idempotency-Key header on writes, Retry-After on 429 and a written three-month deprecation notice suit an agent that retries. Access is the limitation. No price or self-serve signup is published, the general Accounting API is closed to new clients, and API keys carry no scopes.

QuickBooks Online API + MCP

Official MCP server from Intuit with 145 tools and flags to remove write, update or delete tools. Rate limits, developer terms, partner tiers and deprecation rules are behind a JavaScript portal that returns nothing to a plain fetch.

Codat

1. Send Authorization: Basic <base64 of the API key> to https://api.codat.io. The Portal shows the ready-made header value
2. Send a new GUID as Idempotency-Key on every POST and PATCH, and reuse the same key when retrying after a 429
3. Treat writes as asynchronous on most APIs. Keep the push operation key and wait for the {dataType}.write.successful or .unsuccessful webhook
4. Call the Get model (options) endpoint for the connection before a create or update, because required fields differ by accounting package
5. Filter with query=modifiedDate>... and keep pageSize at 100. The daily quota is 1,000 requests times one plus the number of active connected companies

QuickBooks Online API + MCP

1. Store the realmId with the tokens. Every URL needs it and the token alone doesn't name the company
2. Persist the new refresh token from every refresh response. The previous one expires 24 hours later
3. Use the query endpoint with MAXRESULTS and STARTPOSITION for reads rather than fetching by id
4. Send a unique requestid query parameter on writes, so a retry returns the first response instead of posting twice
5. On 429, wait for Retry-After before retrying, and don't retry other 4xx errors