Flight Search Strategy

Search ALL Sources for EVERY Flight Search

This is not a pick-one list. Each source returns different results, different prices, and different airlines. Missing a source means missing options. The priority order determines which price to trust when sources disagree, not which sources to skip.

The Standard Flight Search Workflow

Run ALL of these in parallel: Duffel + Ignav + Google Flights + Skiplagged + Kiwi.

Skiplagged and Kiwi are keyless MCP servers — they are available in every properly launched session. Attempt the tool call before ever claiming MCP is unavailable, and never substitute improvised browser scraping for these sources (see fallback-and-resilience).

Always add Seats.aero for award comparison. Always run the Southwest skill if SW flies the route.

Don't skip sources. Don't assume one source has everything. Present the combined results with the best options highlighted regardless of which source found them.

For a single unified comparison, use the compare-flights skill which orchestrates all of the above in parallel and applies transfer partner optimization.

Round Trip vs One-Way Construction

When the trip has a return date, price BOTH constructions — proactively, without being asked:

1. The round-trip fare on every source (Duffel, Ignav, Kiwi, Skiplagged, and Google Flights all quote returns).
2. Two one-ways, searched independently — which also surfaces the mixed construction (outbound on carrier A, return on carrier B) that round-trip searches can't see.

Run all of it in the same parallel batch; it's two extra searches, not a second pass.

Which wins is route-dependent, so never assume:

• Round trips often win internationally on legacy carriers, where return fares are discounted relative to two one-ways.
• One-way pairs often win domestically, on ULCCs, and anywhere Southwest flies (SW prices every leg as a one-way). They also buy flexibility: each leg can be changed or canceled independently.
• Mixed-carrier pairs frequently beat both when outbound and return are priced by different airlines' sale calendars.

Present the verdict explicitly with the delta: "Round trip $842 vs best one-way pair $918 — book the round trip, saves $76" (or the reverse). If the gap is under ~$50, mention the flexibility advantage of separate tickets before recommending the round trip.

For Southwest Specifically

Use the southwest skill:

docker run --rm ghcr.io/borski/sw-fares --origin SJC --dest DEN --depart 2026-05-15 --points

Or:

python3 skills/southwest/scripts/search_fares.py --origin SJC --dest DEN --depart 2026-05-15 --points

Returns all 4 fare classes (Wanna Get Away, WGA+, Anytime, Business Select), cash and points pricing.

The google-flights skill is a faster fallback for SW cash prices only (no fare class breakdown, no points pricing).

Monitoring Existing Southwest Reservations

docker run --rm -e SW_USERNAME -e SW_PASSWORD \
  ghcr.io/borski/sw-fares change --conf ABC123 --first Jane --last Doe --json

Logs in, selects both legs, and shows fare diffs for every available flight. Negative diffs = savings opportunity. Use --list to discover all upcoming confirmation numbers. Read-only. Never modifies reservations.

Market Selection Strategy

Different country markets return different prices for the same route. Searching from Thailand (&gl=TH) vs the US (&gl=US) can save hundreds of dollars.

Always try multiple markets for international flights:

1. Departure country market first (e.g., &gl=US for flights from the US)
2. Destination country market (e.g., &gl=JP for flights to Japan)
3. Ask the user before trying more (e.g., third countries, VPN markets)

This applies to:

• google-flights via the &gl=XX URL parameter
• ignav via the market field in the search payload

Duffel and SerpAPI don't support market selection.

Source Accuracy Hierarchy

When sources disagree on cash prices:

Duffel > Airline website > SerpAPI > Skiplagged/Kiwi

1. Duffel returns real GDS prices per fare class. These are bookable. Tested: Duffel showed $271 basic / $325 main. SerpAPI showed $541 for the same flight. The gap was consistent across multiple itineraries.
2. SerpAPI (Google Flights) inflates prices. Often shows "main cabin" or bundled fares, not the cheapest bookable fare class. Useful for Google Hotels and destination discovery, but do not trust it as the sole source for flight cash prices.
3. Kiwi returns garbage on small markets. Filter hard or skip Kiwi for domestic routes to small airports.

Common Failure Modes

• Running only one source and missing better options on others.
• Trusting SerpAPI prices as bookable (they're often inflated).
• Skipping Southwest because "no GDS has it" — exactly why you need the SW skill.
• Skipping Seats.aero because the user "doesn't have those points" — they may have them via transfer, see the partner-awards skill.
• Single-market search on international routes (always try at least 2 markets).