MCP server#

Layer runs an MCP server at https://uselayer.sh/mcp. Add it to your AI assistant and it can find matched markets, look one up and check a trade's profit after fees, without you writing any code.

The tools only read. None of them places an order: orders go from the Python SDK on your machine to each venue, with your own keys.

Connect#

You need a Layer API key from your dashboard. The server uses Streamable HTTP and takes your key as a header.

Claude Code

bash

claude mcp add --transport http layer https://uselayer.sh/mcp --header "Authorization: Bearer lyr_your_key"

Cursor (.cursor/mcp.json) and other clients that take a URL:

json

{
  "mcpServers": {
    "layer": {
      "url": "https://uselayer.sh/mcp",
      "headers": { "Authorization": "Bearer lyr_your_key" }
    }
  }
}

Clients that only run local commands can go through mcp-remote:

json

{
  "mcpServers": {
    "layer": {
      "command": "npx",
      "args": ["-y", "mcp-remote", "https://uselayer.sh/mcp", "--header", "Authorization: Bearer lyr_your_key"]
    }
  }
}

Then ask it something like "which NBA games are matched on Kalshi and Polymarket US tonight, and is any of them profitable after fees?"

Tools#

Tool	What it does	Same as
`find_matches`	Lists markets that are the same bet on Kalshi and another venue, earliest event day first, with both venues' live prices and the best trade. Filters: `q`, `series`, `category`, `venue`, `from`, `to`, `limit`, `offset`; page with `next_offset` while `has_more` is true.	`GET /v0/matches`
`lookup_match`	Finds one market's twin on another venue from its `venue` and `market_id`, with the confidence, the rule differences and live prices. Once it has settled, says how both venues settled it.	`GET /v0/match`
`check_profit`	Works out a trade's profit after both venues' fees from `contracts` and each side's price.	`POST /v0/profit`

Each tool answers with the same JSON as its endpoint, so the API reference describes every field.

Keys, limits and errors#

A tool call counts as an API call on your key: the same 60 requests per minute, and the same access to live prices as your account has.

When a call fails, the tool gives your assistant the API's own error, with detail (what's wrong) and hint (how to fix it), so it can correct itself. Without a key, your assistant can still connect and see the tools; calling one answers with where to get a key.

No account? An agent can also pay per call over x402, with no key.