Texas unequal appraisal: median of adjusted comparables
calc_tx_unequal_appraisalEvidence calculation only: not an appraisal or an opinion of value, not legal or tax advice, and not a substitute for the advice of an attorney. The arithmetic of Tex. Tax Code §41.43(b)(3) and §42.26(a)(3), the subject's value against the median appraised value of a reasonable number of comparable properties appropriately adjusted. Takes 3–200 comparables chosen by the caller, each with its roll value and the caller's adjustments (percent, USD amount, or $/SF, each with a reason); optionally normalizes each comparable to value per SF of improvement or land area times the subject's area; applies percentages summed or compounded, then amounts; and returns every comparable's normalized and adjusted value, the sorted list, the median (for an even count, the mean of the two middle values), and the subject's value minus the median in USD (subject_minus_median) and as a fraction of the median (subject_minus_median_pct: 0.1554 means 15.54%, a decimal like every rate in FactLot, not 0.1554%), with the statutes cited. Warns on mixed value bases, §42.26(d) and the §23.231 limitation, comparables in another county, fewer than 5 comparables, total adjustments over 25%, a comparable identical to the subject, no adjustments at all (the median is then unadjusted), and, with normalize_by none, a comparable whose area differs from the subject's by more than 25%. Each comparable row carries flags (code and sentence, facts about the inputs, never a reason the tool drops anything): value per SF more than twice or less than half the subject's, a land-to-improvement area ratio more than twice or less than half the subject's, an area the subject has but the comparable lacks. Optional label (up to 80 characters) and address (up to 120) on the subject and each comparable are echoed in the result (subject_label, subject_address, comparables[i].label and .address) for reports. registry_tx_equity_candidates returns calc_args, its candidates in this tool's input shape, for the caller to review and edit before calling this tool. It does not choose comparables, invent adjustments, or say whether to protest. Deterministic: use this instead of doing the math yourself; cite formula calc.tx_unequal_appraisal@1 and the returned steps, and surface any warnings.
Tool call template
Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.
{
"id": 1,
"jsonrpc": "2.0",
"method": "tools/call",
"params": {
"arguments": {
"tax_year": "<tax_year>",
"subject": "<subject>",
"comparables": "<comparables>"
},
"name": "calc_tx_unequal_appraisal"
}
}Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| subject | Yes | The property whose value is compared. | |
| tax_year | Yes | Tax year of the values compared, e.g. 2027. Decides which text of §42.26(d) applies. | |
| comparables | Yes | The comparable properties, 3 to 200, chosen by the caller. Values must be on the same basis as the subject's. | |
| normalize_by | No | "none" compares whole values. "improvement_area_sf" or "land_area_sf" converts each comparable to value per SF of that area and multiplies by the subject's same area before adjusting; the subject and every comparable must then have that area. | none |
| adjustment_combine | No | "sum" adds a comparable's percentage adjustments and applies the total once (the usual adjustment grid); "compound" multiplies (1 + each percentage). | sum |