# Flight search with [flights_search](../reference/flights_search.md#serpapi_search_tools.flights_search)

[flights_search](../reference/flights_search.md#serpapi_search_tools.flights_search) searches Google Flights for a known origin, destination, and outbound date. It supports one-way and round-trip itineraries with semantic cabin and passenger fields.


# When to use it

Use it when the route is known and the agent needs itineraries, prices, airlines, stops, or duration. Choose [`travel_explore_search`](travel_explore_search.md) when the destination is not decided.

This tool supports one-way and round-trip searches. Multi-city itineraries are not currently supported.


# Quick example

``` python
from serpapi_search_tools import flights_search

flight_tool = flights_search(
    default_params={"currency": "USD", "hl": "en"},
)
agent_tools = [flight_tool]
```

Example invocation:

``` json
{
  "departure_id": "LAX",
  "arrival_id": "AUS",
  "outbound_date": "2030-08-01",
  "return_date": "2030-08-04",
  "travel_class": "business",
  "adults": 1
}
```


# Inputs the agent can provide

| Field | Type | Required | Default and constraints |
|----|----|----|----|
| `departure_id` | string | yes | Specific airport IATA code such as `LHR`, or an exact city Google Knowledge Graph location ID (KGMID) beginning with `/m/` or `/g/`, such as `/m/04jpl` for London; metropolitan codes such as `LON` are unsupported; see the [Google Flights API](https://serpapi.com/google-flights-api); comma-separated values are supported |
| `arrival_id` | string | yes | Specific airport IATA code such as `CDG`, or an exact city KGMID beginning with `/m/` or `/g/`, such as `/m/05qtj` for Paris; metropolitan codes such as `PAR` are unsupported; see the [Google Flights API](https://serpapi.com/google-flights-api); comma-separated values are supported |
| `outbound_date` | date string | yes | Future date in `YYYY-MM-DD` format |
| `return_date` | date string | no | Provide for a round trip; omit for one way; must not be before outbound |
| `travel_class` | enum | no | `economy`; also `premium_economy`, `business`, or `first` |
| `adults` | integer | no | `1`; at least `1` |
| `children` | integer | no | `0`; cannot be negative |
| `infants_in_seat` | integer | no | `0`; cannot be negative |
| `infants_on_lap` | integer | no | `0`; cannot be negative |

Three-letter alphabetic airport codes are normalized to uppercase. City-wide searches require a KGMID, such as `/m/04jpl` for London or `/m/05qtj` for Paris; `LON` and `PAR` are metropolitan codes rather than specific airport codes. Omitting `return_date` makes the request one way; supplying it makes the request a round trip.


# Configure the tool

| Constructor option | Default | Use it for |
|----|----|----|
| `provider` | `"auto"` | Detect one installed SDK or select one explicitly |
| `default_params` | `None` | Fix currency, locale, stops, airline, bag, or time filters supported by SerpApi |
| `mode` | `compact` | Return the main flight result sections; use [SearchResultMode.FULL](../reference/SearchResultMode.md#serpapi_search_tools.SearchResultMode.FULL) to keep supporting sections and all fields on retained results |
| `response_format` | `markdown` | Return Markdown by default, or use [SearchResultFormat.JSON](../reference/SearchResultFormat.md#serpapi_search_tools.SearchResultFormat.JSON) for structured fields |
| `result_limit` | `10` | Maximum entries retained independently from `best_flights` and `other_flights` in either mode |
| `api_key` | `None` | Override environment key lookup |
| `timeout` | `None` | Set the built-in client timeout |
| `client` | `None` | Add caching, logging, testing, or response compaction |
| `include_examples` | `True` | Add a route-search hint to the description |
| `name` | `"flights_search"` | Rename a configured route capability |


# Useful SerpApi parameters

This tool keeps price display predictable:

``` python
from serpapi_search_tools import flights_search

us_flights = flights_search(
    default_params={"currency": "USD", "hl": "en", "gl": "us"},
    name="us_flights",
)
```

SerpApi also supports airline, stops, baggage, maximum price, departure time, arrival time, and other filters. The package validates common conflicts: for example, include and exclude airline lists cannot both be set, return-time filters need a round trip, and bag counts cannot exceed eligible passengers.


# What comes back

Both modes apply `result_limit` independently to `best_flights` and `other_flights`, keeping up to 10 itineraries in each list by default. Flight legs and layovers within an itinerary are not shortened. Use full mode for supporting sections such as price insights, airports, and metadata. Add `result_limit=None` to keep every returned itinerary.


# Common mistakes

- Flight searches use structured route and date fields; there is no `q` input.
- Omitting the route or outbound date.
- Using a metropolitan code such as `LON` or `PAR` instead of a specific airport code or city KGMID.
- Supplying a return date before outbound.
- Asking for multi-city itineraries through this one-route schema.
- Combining both `include_airlines` and `exclude_airlines` defaults.
- Travel dates must be in the future.


# Official SerpApi documentation

- [Google Flights API](https://serpapi.com/google-flights-api)

See the [direct travel example](examples.md) and the [OpenAI Agents travel planner](../docs/sdk-examples/openai_agents.md).