Direct answer

Use GET /agent/sources, GET /agent/tools and GET /agent/mcp/config for discovery. To call a tool, POST a JSON-RPC tools/call message to https://api.spyn3.com/agent/mcp with your API key.

Discovery endpoints

GET/agent/sourcesThe workspace's connected sources.
GET/agent/toolsSPYN3's own tools and the permission each requires.
GET/agent/mcp/configA ready-to-paste MCP client configuration for this endpoint.

Calling tools

The MCP endpoint is stateless — no session to open first — so a single request is enough:

Open a sourceshell
curl https://api.spyn3.com/agent/mcp \
  -H "Authorization: Bearer $SPYN3_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call",
       "params":{"name":"enable_toolset","arguments":{"source":"postgres"}}}'
Call one of its toolsshell
curl https://api.spyn3.com/agent/mcp \
  -H "Authorization: Bearer $SPYN3_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":2,"method":"tools/call",
       "params":{"name":"postgres/query",
                  "arguments":{"sql":"select count(*) from orders"}}}'

Use tools/list to see the exact names and input schemas. Clients on MCP revision 2026-07-28 may also send Mcp-Method and Mcp-Name headers. If they are present, they must match the body.

Errors

  • 401: missing, unknown or revoked key.
  • 403: the key lacks the permission the request needs. A tool outside the key's permission or source scope doesn't exist for that key, so calling it returns an unknown-tool error.
  • 429: over 120 requests a minute. Retry shortly.
  • 402: the Free plan's monthly calls are spent. Retrying won't help until the month turns or the plan is upgraded.
  • A JSON-RPC error naming the source: the upstream failed, and the message says how.

Script it

One key, every connected system

Create a read-only key and query any connected source from a script, a cron job or a CI step.

Start free