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Fli’s MCP server provides two tools for searching flight data. Both tools return real-time results from Google Flights.

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search_flights

Search for flights between two airports on a specific date. Returns a list of available flights with prices, durations, and leg details.

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Parameters

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origin
string
required
Departure airport IATA code (e.g., ‘JFK’, ‘LAX’, ‘SFO’)
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destination
string
required
Arrival airport IATA code (e.g., ‘LHR’, ‘NRT’, ‘CDG’)
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departure_date
string
required
Outbound travel date in YYYY-MM-DD format (e.g., ‘2026-03-15’)
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return_date
string
Return date in YYYY-MM-DD format. Omit for one-way flights.
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departure_window
string
Preferred departure time window in ‘HH-HH’ 24-hour format (e.g., ‘6-20’ for 6am to 8pm). Uses the configured default if not specified.
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airlines
list[string]
Filter results by airline IATA codes (e.g., [‘BA’, ‘AA’, ‘UA’]). Omit to search all airlines.
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cabin_class
string
default:"ECONOMY"
Cabin class preference. Options:
  • ECONOMY - Standard economy seating
  • PREMIUM_ECONOMY - Premium economy with extra legroom
  • BUSINESS - Business class
  • FIRST - First class
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max_stops
string
default:"ANY"
Maximum number of stops allowed. Options:
  • ANY - Include all flight options
  • NON_STOP - Direct flights only
  • ONE_STOP - Up to one connection
  • TWO_PLUS_STOPS - Up to two or more connections
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sort_by
string
default:"CHEAPEST"
How to sort the results. Options:
  • CHEAPEST - Lowest price first
  • DURATION - Shortest flight time first
  • DEPARTURE_TIME - Earliest departure first
  • ARRIVAL_TIME - Earliest arrival first
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passengers
integer
default:"1"
Number of adult passengers. Must be at least 1.

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Response format

Returns a JSON object with the following structure: 
{
  "success": true,
  "flights": [
    {
      "price": 450.50,
      "currency": "USD",
      "legs": [
        {
          "departure_airport": "JFK",
          "arrival_airport": "LHR",
          "departure_time": "2026-03-15T18:30:00",
          "arrival_time": "2026-03-16T06:45:00",
          "duration": "7h 15m",
          "airline": "BA",
          "flight_number": "BA178"
        }
      ]
    }
  ],
  "count": 1,
  "trip_type": "ONE_WAY"
}

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Example usage

Search for flights from JFK to LHR on March 15th, 2026

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search_dates

Find the cheapest travel dates between two airports within a date range. Returns a list of dates with their prices, useful for flexible travel planning.

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Parameters

​
origin
string
required
Departure airport IATA code (e.g., ‘JFK’, ‘LAX’, ‘SFO’)
​
destination
string
required
Arrival airport IATA code (e.g., ‘LHR’, ‘NRT’, ‘CDG’)
​
start_date
string
required
Start of the date range to search in YYYY-MM-DD format (e.g., ‘2026-04-01’)
​
end_date
string
required
End of the date range to search in YYYY-MM-DD format (e.g., ‘2026-04-30’)
​
trip_duration
integer
default:"3"
Trip duration in days for round-trip searches. Only used when is_round_trip is true. Must be at least 1.
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is_round_trip
boolean
default:"false"
Whether to search for round-trip flights. Set to true to find round-trip prices, false for one-way.
​
airlines
list[string]
Filter results by airline IATA codes (e.g., [‘BA’, ‘AA’, ‘UA’]). Omit to search all airlines.
​
cabin_class
string
default:"ECONOMY"
Cabin class preference. Options:
  • ECONOMY - Standard economy seating
  • PREMIUM_ECONOMY - Premium economy with extra legroom
  • BUSINESS - Business class
  • FIRST - First class
​
max_stops
string
default:"ANY"
Maximum number of stops allowed. Options:
  • ANY - Include all flight options
  • NON_STOP - Direct flights only
  • ONE_STOP - Up to one connection
  • TWO_PLUS_STOPS - Up to two or more connections
​
departure_window
string
Preferred departure time window in ‘HH-HH’ 24-hour format (e.g., ‘6-20’ for 6am to 8pm). Uses the configured default if not specified.
​
sort_by_price
boolean
default:"false"
Whether to sort results by price (lowest first). Set to true for price-sorted results.
​
passengers
integer
default:"1"
Number of adult passengers. Must be at least 1.

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Response format

Returns a JSON object with the following structure: 
{
  "success": true,
  "dates": [
    {
      "date": "2026-04-05",
      "price": 425.00,
      "currency": "USD",
      "return_date": "2026-04-12"
    },
    {
      "date": "2026-04-08",
      "price": 438.50,
      "currency": "USD",
      "return_date": "2026-04-15"
    }
  ],
  "count": 2,
  "trip_type": "ROUND_TRIP",
  "date_range": "2026-04-01 to 2026-04-30",
  "duration": 7
}

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Example usage

What are the cheapest dates to fly from SFO to NRT in April?

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Error handling

Both tools return error information in the response when searches fail: 
{
  "success": false,
  "error": "Invalid airport code: XXX",
  "flights": []  // or "dates": []
}
Common errors:
  • Invalid airport codes: Use 3-letter IATA codes (e.g., ‘JFK’ not ‘New York’)
  • Invalid date format: Use YYYY-MM-DD format
  • Invalid parameter values: Check the allowed values for cabin_class, max_stops, etc.
  • Rate limiting: The server automatically retries, but very frequent searches may fail

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Rate limits

The MCP server has a built-in rate limit of 10 requests per second with automatic retry logic. If you encounter rate limit errors:
  • Wait a few seconds between searches
  • The server will automatically retry with exponential backoff
  • Consider spacing out multiple consecutive searches

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Next steps

Configuration

Customize default values and behavior

Setup guide

Configure the MCP server with Claude Desktop

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