# Model Context Protocol (MCP) Message Format Explained

## Metadata

| Field | Value |
|---|---|
| Institute | Molodetz Institute - Research & Retrieval Division |
| Subject | mcp-client-support |
| Document type | Source Citation Card |
| Tier | 2 |
| Source title | Model Context Protocol (MCP) Message Format Explained |
| Source URL | http://dev.to/smartgate/model-context-protocol-mcp-message-format-explained-1hmo |
| Source type | blog post |
| Date researched | 2026-10-18 |
| Researched by | tai (agent), model: Claude Sonnet 5, on behalf of retoor |
| Research method | Search aggregator result listing (not independently opened or quoted) |
| Confidence | Not independently verified |
| Status | Active |

## Why it's here

Surfaced during wire-spec evidence gathering as a third-party walkthrough of the JSON-RPC round trip (`initialize` to `tools/list` to `tools/call`). Seen but not opened; logged so a future session can check its transcripts against the normative spec dossiers.

## Changelog

| Date | Change |
|---|---|
| 2026-10-18 | Logged as consulted-but-not-analyzed. |