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Every API has the same shape: one key, REST under /v1, MCP at /mcp, an OpenAPI 3.1 document and a public /status.

1. Get a key

Keys are free, and you create them on the site: sign up with your email. The sign-up has a bot check, so an agent cannot make a key for itself. Make the key yourself, then give it to your agent. The key is shown once. To get a key you accept the API Terms of Service. TradeCheck also needs a certification about FCRA use, which you give at sign-up or later on Manage your key, where you can also rotate a key.

2. Call an API

Send the key as Authorization: Bearer <key> or as x-api-key: <key>. Each API lives under its own path:

curl "https://api.elysianintelligence.com/tradecheck/v1/license?state=OR&number=206687" \
  -H "Authorization: Bearer $EP_KEY"

3. Use with Claude, ChatGPT and other MCP clients

One connector gives an agent every tool of every API. Each tool name starts with its API, for example cve_get_cve. The connector URL is:

https://mcp.elysianintelligence.com/mcp

1. Claude (web, desktop and mobile): open Customize, then Connectors. Select +, then add a custom connector, and paste the URL. Select Connect. On Team and Enterprise plans, an owner adds the connector first in Organization settings, then Connectors.
2. ChatGPT: open Plugins, select +, then Add custom MCP server. Paste the URL, choose OAuth, and create the plugin. Your workspace settings must allow custom MCP servers.
3. Claude Code: run claude mcp add --transport http elysianprimus https://mcp.elysianintelligence.com/mcp, then type /mcp to sign in.
4. When you connect, our sign-in page opens. Paste your API key (get a free key if you have none), check the app name and the address that gets access, and approve. The app gets a short-lived token, not your key. To stop the access, revoke the key.

Tool calls count against your key's plan, the same as REST calls. Connecting and listing tools is free. A client that cannot do OAuth can send the key as the Bearer token to the same URL, or use the MCP server of one API at /mcp under its base URL:

{
  "mcpServers": {
    "elysian-cve": {
      "type": "http",
      "url": "https://api.elysianintelligence.com/cve/mcp",
      "headers": {
        "Authorization": "Bearer ${EP_KEY}"
      }
    }
  }
}

4. Read errors and limits

Every error has the same body: {"error": {"code", "message"}, "requestId"}. The message is written for you; show it to your users as it is.

1. 400 The input does not match the schema. The message names the field.
2. 401 The key is missing or not valid. 403 The key was revoked, or (TradeCheck only) it has no FCRA certification: tradecheck_certification_required.
3. 402 Prepaid calls are used up, or the plan ended. Buy more.
4. 429 Too many calls in 10 seconds, or the monthly quota is used. Wait for the time in retry-after.

5. Check freshness

Every API answers GET /status without a key: each dataset, when it last loaded, how many rows it holds and the last error. The home page shows these numbers live.

6. Required notices

Section 5.4 of the API Terms of Service asks you to include these notices wherever you show or pass on the data, and to follow the licence of each source below.

MIT License

Copyright (c) 2022 FIRST.Org, Inc.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

Sources and licences of each API

Citing HomeSignal data

This is a request, not a term of section 5.4. Please cite the agency of each HomeSignal value, as its citation field gives it. For BLS data, please keep the date in retrieved_at and this statement, which the BLS API terms ask us to make:

BLS.gov cannot vouch for the data or analyses derived from these data after the data have been retrieved from BLS.gov.