---
title: "Send an MCP JSON-RPC message"
method: POST
path: "/mcp"
tags: ["mcp"]
---

# Send an MCP JSON-RPC message

`POST /mcp`

## Request

- Base URL: `https://hangingcontext.com`
- URL: `https://hangingcontext.com/mcp`
- Auth: none required

Send an MCP message over Streamable HTTP. Send initialize first. The tools are hc_ask, hc_latest, hc_since, hc_search, hc_get_story, hc_sources, hc_topics, hc_about.

## Headers

- `HC-API-Version` '1'

## Request body

- JsonRpcRequest: A JSON-RPC 2.0 request for the MCP server.
  - `jsonrpc` '2.0', required
  - `id` union
    - string
    - integer
  - `method` string, required
  - `params` object

## Response `200`

The JSON-RPC response, as JSON or as text/event-stream.

- JsonRpcResponse: A JSON-RPC 2.0 response from the MCP server.
  - `jsonrpc` '2.0', required
  - `id` union
    - string
    - integer
  - `result` object
  - `error` object
    - `code` integer
    - `message` string

## Other responses

- `400`: The request is not valid.
- `429`: Too many calls from this address. Wait, then call again.
- `500`: The server could not answer. Try again later.

---

[API](https://skmtc.dev/hangingcontext/apis/hanging-context-public-read-api.md) · [All operations](https://skmtc.dev/hangingcontext/apis/hanging-context-public-read-api/llms.txt) · [OpenAPI document](https://skmtc.dev/hangingcontext/apis/hanging-context-public-read-api/revisions/48912c502036?raw)