For AI agents

Give your assistant a compatibility check

Tethered Trust is a remote MCP server and a plain HTTP API. Agents call it before recommending or buying a part, and get a verdict with evidence instead of a guess. Free during early access; no key needed.

MCP server URL

https://tetheredtrust.com/mcp

Streamable HTTP, stateless, no authentication needed during the launch. An API key raises rate limits.

Claude

Claude (web or desktop): Settings › Connectors › Add custom connector, then paste the URL above.

Claude Code

claude mcp add --transport http tethered-trust https://tetheredtrust.com/mcp

ChatGPT

In developer mode, add a custom connector and paste the URL above. No authentication is needed.

Cursor

~/.cursor/mcp.json

{
  "mcpServers": {
    "tethered-trust": {
      "url": "https://tetheredtrust.com/mcp"
    }
  }
}

VS Code

.vscode/mcp.json

{
  "servers": {
    "tethered-trust": {
      "type": "http",
      "url": "https://tetheredtrust.com/mcp"
    }
  }
}

Tools

Tool	What it does	Price
`how_it_works`	What Tethered Trust is, what it covers, pricing and terms, and how an assistant should use it before a purchase. Call once if unsure; you don't need it for every check.	Free
`list_coverage`	Which product categories and models are in the compatibility graph, with counts. Pass a category to list its models. Covers computers & consoles (RAM, M.2 SSDs, USB-C chargers), phones/tablets/watches (USB-C PD, MagSafe, Qi2, watch bands), cameras (lens mounts, adapters, batteries, memory cards), cordless power tools (battery platforms, batteries, chargers), printers (ink, toner, drums), appliances (refrigerator filters, installation fit) and smart home (Matter, Thread, Zigbee, HomeKit, Alexa, Google Home, bulb bases).	Free
`resolve_product`	Look up one product in the Tethered Trust graph by name or model number and get its structured specs, what it accepts (mounts, battery platforms, cartridges, protocols) and what it fits.	Free
`check_compatibility`	Will this exact part or accessory work with that exact device? Use before recommending or buying. Covers computers & consoles (RAM, M.2 SSDs, USB-C chargers), phones/tablets/watches (USB-C PD, MagSafe, Qi2, watch bands), cameras (lens mounts, adapters, batteries, memory cards), cordless power tools (battery platforms, batteries, chargers), printers (ink, toner, drums), appliances (refrigerator filters, installation fit) and smart home (Matter, Thread, Zigbee, HomeKit, Alexa, Google Home, bulb bases). Returns a verdict (compatible / compatible_with_caveats / incompatible / uncertain / needs_detail) with confidence, the rules checked, caveats and evidence links.	Free now $0.05 on paid endpoints
`find_parts`	Which parts and accessories fit this model? OEM parts first, then verified alternatives: e.g. a refrigerator's water filter, a printer's cartridges, a camera's lenses and batteries, a tool's batteries, or the RAM, SSDs and chargers that fit a computer.	Free now $0.05 on paid endpoints
`check_fit`	Will this appliance physically fit this space? Compares dimensions plus typical installation clearances and required connections (power, water, gas).	Free now $0.05 on paid endpoints
`verify_receipt`	Check a Tethered Trust receipt: is the signature ours, is it still within valid_until, and have the records behind it changed since? A valid receipt proves what we said and when; it doesn't guarantee the verdict was right.	Free
`report_outcome`	After a purchase, report whether it actually fit. Free, safe to call, and only the first report per check counts. Reports are weighted by level: self_reported (website), agent_reported (anonymous API/MCP), partner_reported (API key holders) and order_confirmed (order evidence we've confirmed). Only the last two can raise future confidence.	Free

Paid endpoints (/v1/paid/*) accept x402 payments in USDC or prepaid credits; see pricing. The free endpoints stay free during early access. Every tool has the same HTTP endpoint: see /v1 and llms.txt.

Receipts

Every check returns a receipt: a signed record (EdDSA JWS) of the verdict, the products as identified, the evidence and a valid_until date. Check one with verify_receipt or POST /v1/receipts/verify; public keys are at /.well-known/tethered-trust-keys.json. A receipt proves what we said and when, not that it's right.

Try it over HTTP

curl -X POST https://tetheredtrust.com/v1/check \
  -H 'Content-Type: application/json' \
  -d '{"existing":"Sony A7 IV","candidate":"Canon RF 24-105mm f/4L"}'

Request an API key

Keys raise the hourly limit from 60 to 1,200 calls and will carry over to paid plans.

Use is subject to the API & Agent Terms. Answers are informational; relay caveats and confidence honestly.