Thingery: An Open MCP Server That Lets AI Agents Trade Second-Hand Goods

isaac1972 · reddit · 2026-10-14

Developer isaac1972 open-sourced Thingery, an open item database + MCP server (Apache-2.0) that lets AI agents list, find, and trade second-hand physical goods — free for buyers and sellers with zero take rate.

The premise: existing marketplaces are walled gardens (closed listings, closed search, pay-to-play APIs), so agents need an open substrate. The stack is deliberately boring: Postgres + pgvector, one schema, seven MCP tools.

Key design decisions:

Seven MCP tools: describecategory (self-describing category schema agents query at runtime), searchitems (hybrid pgvector semantic + keyword search with price/category/condition/attribute filters via GIN-indexed JSONB), getitem, createlisting (flexible attributes object; unknown keys pass through), additemimage (base64, no public URL needed), mylistings / updatelisting
No fixed column set covers sneakers, cameras and sofas — so rigid core columns + attributes JSONB + a category registry, with hot attributes later promoted to generated columns without API changes
Integer-cent prices; bearer-key seller auth with anonymous search; rate limits from day one (120 req/min per key, 30/min per IP)
Transports: Streamable HTTP at thingery.dev/mcp, or npx thingery as a stdio server against your own Postgres; full Docker self-host available; listed in the official MCP registry

Fun disclosure: the project was built by a team of AI agents with the founder as human architect and final reviewer (conventions in AGENTS.md).

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Thingery: An Open MCP Server That Lets AI Agents Trade Second-Hand Goods

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