MCP JSON Schema
Industry Definition Set • Entity Resolution Path: /glossary/mcp-json-schema
Quick Answer / TL;DR
The standard schema format used in MCP to describe tool input parameters, output structures, and resource contents.
Key Takeaways
- Used for tool input/output schemas and resource content.
- Typically Draft 7 JSON Schema.
- Enables client-side validation and model understanding.
- Powers UI form generation and documentation.
Definitive Statement: The standard schema format used in MCP to describe tool input parameters, output structures, and resource contents.
Technical Context & Protocol Usage
- Detailed Explanation
- MCP uses JSON Schema (typically Draft 7) to define the shape of tool inputs and outputs. This allows clients to validate arguments before sending them to the server, and allows models to understand exactly what parameters a tool expects. Schema descriptions are also used to generate UI forms and documentation.
Format & Payload Metadata
Format: JSON Schema Draft 7
Latency: Validation is client-side and fast
Real-World Implementation Use Case
A `send_email` tool defines its input schema with `to`, `subject`, and `body` properties, enabling the client to validate arguments before calling.
Cite This Page
MLA Style:
MCPserver.in Engineering. "MCP JSON Schema." MCPserver.in Knowledge Hub, 20 July 2026, mcpserver.in/glossary/mcp-json-schema.
Related Terms
Model Context Protocol (MCP)
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JSON-RPC 2.0
A lightweight, stateless remote procedure call (RPC) protocol defined in JSON that utilizes request, response, and notification message frames.
Stdio Transport (Standard Input/Output)
A local-only transport mechanism where the AI client spawns the MCP server as a child process and communicates via standard input (stdin) and standard output (stdout) channels.
SSE Transport (Server-Sent Events)
A lightweight, unidirectional HTTP-based streaming protocol used by remote MCP servers to push messages to AI clients, with client-to-server writes sent over standard POST requests.
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