Marketplace

Navigate online marketplaces as buyer, seller, or builder with platform comparison, listing optimization, and scam detection.

Security Scan

This is an instruction-only, role-based marketplace guidance skill whose requested resources and instructions align with its stated purpose and contain no hidden installs, credentials, or file access.

Purpose & Capability

The name/description (marketplace buyer/seller/builder guidance) match the provided files (buyer.md, seller.md, builder.md, arbitrage.md, compliance.md). No unrelated binaries, env vars, or config paths are requested.

Instruction Scope

SKILL.md and content files consist of prose guidance and checklists. Instructions do not ask the agent to read local files, environment variables, or transmit data to external endpoints beyond the agent's normal behavior. The guidance correctly emphasizes verifying real-time marketplace data, but doesn't mandate any hidden actions or data exfiltration.

Install Mechanism

No install spec and no code files — instruction-only. Nothing will be downloaded or written to disk by the skill itself.

Credentials

The skill declares no required credentials, binaries, or config paths. There are no environment variables requested that would be disproportionate to providing marketplace advice.

Persistence & Privilege

always is false and model invocation is default-enabled (normal). The skill does not request permanent system presence or modify other skills or system-wide settings.

Assessment

This skill is instruction-only and internally consistent with its stated purpose, so technical risk is low. Before installing, note: (1) the guidance is general and may be jurisdiction-specific — do not treat it as legal or tax advice; consult a professional for taxes, legal structure, or liability questions; (2) marketplace policies and thresholds change frequently — verify prices, fees, and ToS in real time before acting; (3) the skill can be invoked by the agent (normal behavior), so consider whether you want automated advice/actions enabled for your agent; and (4) watch for any follow-up prompts that ask you to paste credentials or upload sensitive files — those would be out of scope and should be rejected.

Architecture

Role-based guidance for marketplace participation. Load relevant file based on user's role.

marketplace/
├── buyer.md      # Price comparison, scam detection, negotiation
├── seller.md     # Listing creation, pricing, platform rules
├── builder.md    # Marketplace creation, economics, liquidity
├── arbitrage.md  # Price gaps, ROI calculations, ToS risks
└── compliance.md # Tax obligations, legal pitfalls, bans

Quick Reference

Role	File	When to Load
Buying items	buyer.md	Comparing prices, spotting scams, negotiating
Selling items	seller.md	Creating listings, pricing, handling buyers
Building marketplace	builder.md	Designing platform, economics, payments
Arbitrage/Reselling	arbitrage.md	Finding price gaps, calculating true ROI
Legal/Tax questions	compliance.md	Tax nexus, ToS violations, suspensions

Core Rules

1. Platform-Specific, Never Generic

• Each platform has unique fees, rules, and dynamics
• eBay auction ≠ Amazon Buy Box ≠ FB Marketplace negotiation
• ALWAYS specify which platform advice applies to

2. Total Cost, Not Sticker Price

• Include: platform fees, shipping, taxes, return costs
• Amazon referral fee varies 8-45% by category
• eBay 13%+ Poshmark 20%+ Mercari varies

3. Scam Pattern Recognition

• Stock photos on local marketplaces = red flag
• "Ship to my address, I'll pay extra" = triangulation fraud
• Payment outside platform = no protection
• New account + high-value item + urgency = likely scam

4. Pricing Research = SOLD, Not Listed

• Listed prices mean nothing—items don't sell at listed price
• Always research completed/sold listings
• Factor in condition: "Good" vs "Very Good" = 30% price difference

5. Suspension Risks Are Real

• Amazon ODR >1% = account death
• Review manipulation = permanent ban
• IP complaints from brands = immediate suspension
• Multiple accounts = instant termination

6. Fee Complexity

Never estimate fees—calculate exactly:

• Amazon: referral + FBA + storage + return processing + advertising
• eBay: final value (category-specific) + promoted listings + payment
• Factor returns into margin (15-30% in some categories)

7. Real-Time Data Required

• Never quote prices from memory/training data
• Inventory and pricing change hourly
• Competitor stock levels affect optimal pricing
• Always verify current marketplace state before advising