Any way to query for the full merchant details?

For the past few years my app has been receiving Monzo transactions using a webhook. The webhook receives very detailed information about the merchant, for example:

    "merchant": {
      "id": "merch_00009waFN9m2pCC4w2kOLR",
      "group_id": "grp_00009pV2auNOH7io8cDj3S",
      "name": "El Desperado Mexican",
      "logo": "",
      "emoji": "",
      "category": "eating_out",
      "online": false,
      "atm": false,
      "address": {
        "short_formatted": "501 London Road, Sutton SM3 8JR",
        "city": "Sutton",
        "latitude": 51.3713889,
        "longitude": -0.2280556,
        "zoom_level": 17,
        "approximate": false,
        "formatted": "501 London Road, Sutton, England SM3 8JR, United Kingdom",
        "address": "501 London Road",
        "region": "England",
        "country": "GBR",
        "postcode": "SM3 8JR"
      "disable_feedback": false,
      "metadata": {

I’ve now added a feature that queries the API for transactions in case any were missed. But the API only returns the merchant ID:

    'merchant': 'merch_00009waFN9m2pCC4w2kOLR',

Any ideas on how to get the full merchant details?

When querying the API for the transaction you can add an expand parameter specifying merchant as the value. This will provide the same information that you receive in the webhook.