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The MCP server can be customized using environment variables. All configuration is optional and has sensible defaults.

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Environment variables

All configuration variables use the FLI_MCP_ prefix.

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FLI_MCP_DEFAULT_PASSENGERS

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FLI_MCP_DEFAULT_PASSENGERS
integer
default:"1"
Default number of adult passengers for searches. Must be at least 1.
FLI_MCP_DEFAULT_PASSENGERS=2

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FLI_MCP_DEFAULT_CURRENCY

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FLI_MCP_DEFAULT_CURRENCY
string
default:"USD"
Three-letter currency code returned with search results. Must be exactly 3 characters.
FLI_MCP_DEFAULT_CURRENCY=EUR

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FLI_MCP_DEFAULT_CABIN_CLASS

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FLI_MCP_DEFAULT_CABIN_CLASS
string
default:"ECONOMY"
Default cabin class when none is specified. Options:
  • ECONOMY
  • PREMIUM_ECONOMY
  • BUSINESS
  • FIRST
FLI_MCP_DEFAULT_CABIN_CLASS=BUSINESS

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FLI_MCP_DEFAULT_SORT_BY

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FLI_MCP_DEFAULT_SORT_BY
string
default:"CHEAPEST"
Default sorting strategy for flight results. Options:
  • CHEAPEST - Sort by lowest price
  • DURATION - Sort by shortest flight time
  • DEPARTURE_TIME - Sort by earliest departure
  • ARRIVAL_TIME - Sort by earliest arrival
FLI_MCP_DEFAULT_SORT_BY=DURATION

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FLI_MCP_DEFAULT_DEPARTURE_WINDOW

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FLI_MCP_DEFAULT_DEPARTURE_WINDOW
string
Default departure time window in ‘HH-HH’ 24-hour format. If not set, no time restriction is applied.
FLI_MCP_DEFAULT_DEPARTURE_WINDOW=6-20  # 6am to 8pm

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FLI_MCP_MAX_RESULTS

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FLI_MCP_MAX_RESULTS
integer
Maximum number of results returned by each tool. Must be greater than 0. If not set, all results are returned.
FLI_MCP_MAX_RESULTS=10

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Configuration with Claude Desktop

Set environment variables in your Claude Desktop configuration file: 
{
  "mcpServers": {
    "fli": {
      "command": "fli-mcp",
      "args": [],
      "env": {
        "FLI_MCP_DEFAULT_CURRENCY": "EUR",
        "FLI_MCP_DEFAULT_CABIN_CLASS": "BUSINESS",
        "FLI_MCP_DEFAULT_SORT_BY": "DURATION",
        "FLI_MCP_DEFAULT_DEPARTURE_WINDOW": "8-22",
        "FLI_MCP_MAX_RESULTS": "10"
      }
    }
  }
}

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Configuration file locations

macOS: 
~/Library/Application Support/Claude/claude_desktop_config.json
Windows: 
%APPDATA%\Claude\claude_desktop_config.json
Linux: 
~/.config/Claude/claude_desktop_config.json

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Configuration examples

Configure for Euro currency and preferred departure times:
{
  "mcpServers": {
    "fli": {
      "command": "fli-mcp",
      "args": [],
      "env": {
        "FLI_MCP_DEFAULT_CURRENCY": "EUR",
        "FLI_MCP_DEFAULT_DEPARTURE_WINDOW": "9-18"
      }
    }
  }
}
Configure for business class and minimal results:
{
  "mcpServers": {
    "fli": {
      "command": "fli-mcp",
      "args": [],
      "env": {
        "FLI_MCP_DEFAULT_CABIN_CLASS": "BUSINESS",
        "FLI_MCP_DEFAULT_SORT_BY": "DEPARTURE_TIME",
        "FLI_MCP_MAX_RESULTS": "5"
      }
    }
  }
}
Configure for multiple passengers:
{
  "mcpServers": {
    "fli": {
      "command": "fli-mcp",
      "args": [],
      "env": {
        "FLI_MCP_DEFAULT_PASSENGERS": "4",
        "FLI_MCP_DEFAULT_SORT_BY": "CHEAPEST"
      }
    }
  }
}
Focus on cheapest options with limited results:
{
  "mcpServers": {
    "fli": {
      "command": "fli-mcp",
      "args": [],
      "env": {
        "FLI_MCP_DEFAULT_SORT_BY": "CHEAPEST",
        "FLI_MCP_MAX_RESULTS": "3"
      }
    }
  }
}

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FlightSearchConfig class

The configuration is implemented using the FlightSearchConfig Pydantic settings class in fli/mcp/server.py:51. This class:
  • Automatically loads environment variables with the FLI_MCP_ prefix
  • Validates all configuration values
  • Provides type safety for configuration options
  • Exposes defaults through the MCP resource endpoint

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Configuration schema

The server exposes its configuration schema through an MCP resource. AI assistants can query this resource to understand the current configuration: 
{
  "defaults": {
    "default_passengers": 1,
    "default_currency": "USD",
    "default_cabin_class": "ECONOMY",
    "default_sort_by": "CHEAPEST",
    "default_departure_window": null,
    "max_results": null
  },
  "schema": {
    "properties": {
      "default_passengers": {
        "type": "integer",
        "minimum": 1,
        "description": "Default number of adult passengers to include in searches."
      },
      "default_currency": {
        "type": "string",
        "minLength": 3,
        "maxLength": 3,
        "description": "Three-letter currency code returned with search results."
      }
    }
  }
}

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Applying configuration changes

After modifying environment variables:
  1. Save the configuration file
  2. Completely quit Claude Desktop (not just close the window)
  3. Restart Claude Desktop
  4. The new configuration will be loaded automatically

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Validating configuration

You can verify your configuration by asking Claude: 
What is your current Fli configuration?
Claude can access the configuration resource to show you the active settings.

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Next steps

Tool reference

Learn about search parameters and options

Setup guide

Initial installation and configuration

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