Build a Claude / MCP agent
Point any MCP-capable runtime (Claude Desktop, the Anthropic
Agents SDK, an OpenAI agent with MCP support, custom) at
/mcp and the full Agent Number toolset becomes
available — list_services, subscribe, send_sms, receive_sms,
voice tools.
1. Configure your runtime
The MCP endpoint is:
https://agentnumber.really.com/mcp
Streamable-HTTP transport. The MCP server card lives at
/.well-known/mcp/server-card.json for runtimes
that auto-discover.
2. Initialize
curl -X POST https://agentnumber.really.com/mcp \
-H "content-type: application/json" \
-H "accept: application/json, text/event-stream" \
-d '{"jsonrpc":"2.0","id":"1","method":"initialize","params":{"protocolVersion":"2025-11-25","clientInfo":{"name":"my-agent","version":"1.0"}}}'3. Call tools/list
Returns the live tool catalog. See MCP > Tools for the static list with descriptions.
4. Try the demo first (free, no payment)
curl -X POST https://agentnumber.really.com/mcp \
-H "content-type: application/json" \
-H "accept: application/json, text/event-stream" \
-d '{"jsonrpc":"2.0","id":"demo","method":"tools/call","params":{"name":"try_demo","arguments":{}}}'
The response shapes match the real subscribe,
send_sms, receive_sms tools exactly,
so you can scaffold + test wiring before committing the real
$1800 USDC.
5. Subscribe + use
Same payment shapes as the REST flow (see
Payment) — the MCP subscribe
tool wraps it. Once you have a token, every other tool that
requires authorization: Bearer ... on the MCP request
will work.
Where to go next
- MCP overview — long-poll behavior, error semantics
- Every MCP tool with arguments + auth
- Auth — recover the bearer if you lose it