Get the current market value of a vehicle from its VIN using the CarsXE API. Use this when a user asks how much a car is worth, wants to know its value, or is thinking about buying/selling a vehicle.
SkillScore82Maintained
Automatic
◆Research pack
Last verified 9/1/2026
What it changes
Passed 16 of 20 test cases with the skill, and 3 of 20 without it.
Without skill14%
With skill82%
Checks it passed that the model alone missed
Appends query parameter state=CA.
Appends query parameter state=FL.
Appends query parameter state=NY.
and 17 more in the full report
16 fixed2 passed either way3 still failing1 broke
Pass-rate lift
+68 pp
Tokens
+23%
Agent turns
0%
Response time
+28%
Model gemini-3.6-flashMeasured 9/1/2026v118 of 22 cases passed with skill · 20 comparable
Tokens, turns and time describe resource use, not a dollar price.
See it in action
One of 16 test cases the skill fixed. Same model, same prompt, with and without the skill.
1 of 16
Prompt
Look up the market value for VIN 5T3CZ44A00S999999 located in California (CA) with 20,000 miles in clean condition.
What was checked, without and with the skill
Checked
Without skill
With skill
Passes state parameter as state=CA.
Missed
Passed
case-15 · gemini-3.6-flash · 9/1/2026 · answers are capped and redacted
What's inside
The instructions your model reads when the skill loads.
SKILL.md17 linessingle file
When the user asks about a vehicle's price, worth, or market value and has a VIN:
Optionally refine the estimate with these parameters if the user mentions them:
state — US state code (e.g., CA, TX) for regional pricing
mileage — current mileage to adjust the value
condition — vehicle condition: excellent, clean, average, or rough
Make an HTTP GET request to the CarsXE Market Value API:
GET https://api.carsxe.com/v2/marketvalue?key={CARSXE_API_KEY}&vin={VIN}&source=codex_plugin
Append &state=<STATE>, &mileage=<MILEAGE>, and/or &condition=<CONDITION> if provided.
Present the estimated market value clearly, including:
Current value estimate
Low / average / high range if available
Historical trend if available
Provide helpful context (e.g., whether the value is strong for its age/mileage).
If the API key is missing, tell the user to set the CARSXE_API_KEY environment variable (see AGENTS.md).