---
title: "Stateless Streamable HTTP MCP"
method: POST
path: "/mcp"
---

# Stateless Streamable HTTP MCP

`POST /mcp`

## Request

- Base URL: `https://api.theusedcarindex.com`
- URL: `https://api.theusedcarindex.com/mcp`
- Auth: one of:
  - none
  - HTTP bearer
  - API key in header `X-API-Key`

initialize, ping and tools/list require no key; tools/call requires a key. Accept is optional. SDK JSON-RPC errors can use HTTP 200; error.data.status always matches the HTTP status. JSON responses, 64 KB request limit. Same schemas and unit charges as HTTP.

## Request body

- object
  - `jsonrpc` '2.0', required
  - `id` union
    - string
    - number
  - `method` string, required
  - `params` object

## Response `200`

Success

- object: JSON-RPC result or SDK error with error.data.status equal to 200; tool results contain JSON text and structuredContent.

## Other responses

- `202`: Notification accepted
- `400`: JSON-RPC error; data contains a problem. 401 includes WWW-Authenticate: Bearer. 429 includes Retry-After; binding denials use problem+json.
- `401`: JSON-RPC error; data contains a problem. 401 includes WWW-Authenticate: Bearer. 429 includes Retry-After; binding denials use problem+json.
- `403`: JSON-RPC error; data contains a problem. 401 includes WWW-Authenticate: Bearer. 429 includes Retry-After; binding denials use problem+json.
- `404`: JSON-RPC error; data contains a problem. 401 includes WWW-Authenticate: Bearer. 429 includes Retry-After; binding denials use problem+json.
- `413`: JSON-RPC error; data contains a problem. 401 includes WWW-Authenticate: Bearer. 429 includes Retry-After; binding denials use problem+json.
- `415`: JSON-RPC error; data contains a problem. 401 includes WWW-Authenticate: Bearer. 429 includes Retry-After; binding denials use problem+json.
- `429`: JSON-RPC error; data contains a problem. 401 includes WWW-Authenticate: Bearer. 429 includes Retry-After; binding denials use problem+json.
- `500`: JSON-RPC error; data contains a problem. 401 includes WWW-Authenticate: Bearer. 429 includes Retry-After; binding denials use problem+json.
- `503`: JSON-RPC error; data contains a problem. 401 includes WWW-Authenticate: Bearer. 429 includes Retry-After; binding denials use problem+json.

---

[API](https://skmtc.dev/theusedcarindex/apis/the-used-car-index.md) · [All operations](https://skmtc.dev/theusedcarindex/apis/the-used-car-index/llms.txt) · [OpenAPI document](https://skmtc.dev/theusedcarindex/apis/the-used-car-index/revisions/80dd1305d05c?raw)