shipping-rate-shop — independently scanned and version-tracked by SaferSkills.
SaferSkills independently audited shipping-rate-shop (Agent Skill) and scored it 100/100 (green). The audit ran 55 deterministic rules across Security, Supply Chain, Maintenance, Transparency, and Community; it found 0 high-severity and 0 lower-severity findings. The full rule-by-rule trace and per-finding evidence are below. Free, methodology-open.
Findings & checks · 0 flagged
Every scanned point with the score it earned and what moved between them.
First recorded scan — no prior version to compare against.
The primary manifest — the file an agent reads to learn what this artifact does.
You generate a complete multi-carrier shipping pipeline. The 2026 rate landscape rewards rate-shopping: FedEx/UPS/DHL each took +5.9% general rate increases, USPS implemented service-specific changes Jan 18, 2026 plus a temporary 8% surcharge from Apr 26, 2026 through Jan 17, 2027. Static carrier choice leaves money on the table.
Carrier strength heuristics that hold in 2026:
============================================================ === PRE-FLIGHT === ============================================================
Verify:
Recovery:
============================================================ === PHASE 1: RATE SHOP CORE === ============================================================
Generate rate_shop.py (Python) or rateShop.ts (Node):
def rate_shop(parcel, from_addr, to_addr, options={}):
"""
Returns sorted list of carrier+service+rate quotes.
parcel: {weight_oz, length_in, width_in, height_in}
from_addr / to_addr: {name, street1, city, state, zip, country}
options: {residential, signature_required, insurance_amount, saturday_delivery}
"""
quotes = []
for carrier_client in active_carriers():
try:
carrier_quotes = carrier_client.get_rates(parcel, from_addr, to_addr, options)
quotes.extend(carrier_quotes)
except RateRequestError as e:
log.warning(f"{carrier_client.name} rates unavailable: {e}")
return sorted(quotes, key=lambda q: (q['rate_usd'], q['delivery_days']))Each quote has: carrier, service, service_code, rate_usd, delivery_days, est_delivery_date, rate_id (for label purchase later).
VALIDATION: Rate shop returns ≥ 2 carrier quotes for a sample 1-lb domestic shipment. If only 1 returns, surface the others' errors clearly.
============================================================ === PHASE 2: DIMENSIONAL WEIGHT CALCULATION === ============================================================
Dim weight catches teams off-guard. Each carrier has its own divisor:
| Carrier | Domestic divisor | International divisor |
|---|---|---|
| UPS | 139 | 139 |
| FedEx | 139 | 139 |
| USPS | 166 (Priority) | 166 |
| DHL | 139 | 139 |
billable_weight = max(actual_weight_lb, ceil((L × W × H) / divisor))
Always compute and surface dim weight in the quote response so the user knows their effective billing weight, not just actual.
VALIDATION: Dim weight calc matches each carrier's published worksheet for a 14×10×6 box at 2 lb actual.
============================================================ === PHASE 3: ADDRESS VALIDATION === ============================================================
Bad addresses → returned packages → real cost. Run address validation before quoting:
Output: corrected address, residential/commercial flag, deliverability score. Residential flag matters — UPS Ground residential adds ~$5.50/package vs commercial.
VALIDATION: A known-bad address (e.g., "123 Fake St, San Francisco CA") returns deliverability="undeliverable" not silently accepted.
============================================================ === PHASE 4: CARRIER-SPECIFIC SERVICES === ============================================================
Pre-populate the service list per carrier with 2026-current codes:
USPS: Priority Mail, Priority Mail Express, Ground Advantage (replaced Retail Ground + First-Class Package in 2023), Media Mail.
UPS: UPS Ground, 3 Day Select, 2nd Day Air, Next Day Air, Next Day Air Saver, SurePost (USPS final-mile), Worldwide Express/Expedited/Saver/Standard.
FedEx: FedEx Ground, Home Delivery, Express Saver, 2Day, Standard Overnight, Priority Overnight, First Overnight, International Economy/Priority.
DHL eCommerce: SmartMail Parcel Expedited, SmartMail Parcel Plus Expedited, Parcel International Standard/Direct, Express Worldwide.
Each service has cutoff times by zone — show the latest "drop-off by X to ship today" in the quote.
VALIDATION: Service list matches each carrier's 2026 published codes. Cutoff times zone-aware.
============================================================ === PHASE 5: LABEL PURCHASE + TRACKING === ============================================================
Once a quote is selected, generate purchase_label.py:
POST /shipments/{rate_id}/buy).tracking_number, carrier, service, rate_paid, purchased_at, from_addr, to_addr.label_created, picked_up, in_transit, out_for_delivery, delivered, exception, returned).For high-volume shippers, support manifest creation (end-of-day batch close) — required for USPS and reduces per-package fee.
VALIDATION: Buy-and-track round trip works against the carrier sandbox. Status webhook updates the DB within 60s.
============================================================ === PHASE 6: SMART CARRIER ROUTING === ============================================================
Pre-route the user to the right carrier based on package signal:
def recommend_carrier(parcel, dest, urgency):
"""Heuristic-first, rate-shop-validated."""
if parcel.weight_oz < 16 and dest.country == 'US' and urgency >= 3:
candidates = ['USPS_Ground_Advantage', 'UPS_SurePost']
elif parcel.weight_lb > 10 and dest.country == 'US':
candidates = ['UPS_Ground', 'FedEx_Ground']
elif dest.country != 'US' and parcel.weight_lb < 4.4:
candidates = ['DHL_eCommerce', 'USPS_Priority_Intl']
elif urgency == 1: # next day
candidates = ['UPS_Next_Day_Air_Saver', 'FedEx_Standard_Overnight', 'USPS_Priority_Mail_Express']
else:
candidates = ['ALL']
return rate_shop_filtered(candidates)Pair heuristics with rate-shop validation — heuristics narrow the field, real rates make the call.
VALIDATION: Recommendations match published carrier-strength patterns within 90% of test fixtures.
============================================================ === PHASE 7: COST MONITORING === ============================================================
Generate cost_dashboard.sql (or BigQuery / Snowflake equivalent) that reports weekly:
This is where the rate-shop ROI compounds. Without monitoring, savings drift.
VALIDATION: Dashboard query runs against the user's shipping data warehouse and surfaces ≥ 3 actionable findings.
============================================================ === SELF-REVIEW === ============================================================
Score 1–5:
Common gap: failing to compute dim weight → quote looks cheap but actual charge is 2-3× higher. Always surface billable weight.
============================================================ === LEARNINGS CAPTURE === ============================================================
Append to ~/.claude/skills/shipping-rate-shop/LEARNINGS.md:
============================================================ === STRICT RULES === ============================================================
~30 seconds. Free. No account. Every finding cites a rule and a line of evidence.