MCP Schema Version Support #14970
Description
What happened?
The Rust rmcp MCP server library updated the default schema sent with the MCP request:
https://github.com/modelcontextprotocol/modelcontextprotocol/pull/655/files#top
previously this was:
http://json-schema.org/draft-07/schema#
now it sends:
https://json-schema.org/draft/2020-12/schema
which gives a transient error in Gemini CLI:
/mcp schema
Configured MCP servers:
🟢 HelloStdio - Ready (1 tool)
Tools:
- greeting
Hello World via Model Context Protocol
Parameters:
{
"type": "object",
"properties": {
"message": {
"description": "hello world",
"type": "string"
}
},
"required": [
"message"
],
"$schema": "https://json-schema.org/draft/2020-12/schema",
"title": "GetMsgRequest"
}
greetings from earth
╭───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╮
│ x greeting (HelloStdio MCP Server) {"message":"greetings from earth"} │
│ │
│ no schema with key or ref "https://json-schema.org/draft/2020-12/schema" │
╰─────────────────────────────────────────────────────────────────────────────────
What did you expect to happen?
Gemini CLI would accept the updated schema and proceeed
Client information
Client Information
Run gemini to enter the interactive CLI, then run the /about command.
> /about
rmcp = { version = "0.11.0", features = ["auth", "server","macros", "transport-io"] }
Login information
No response
Anything else we need to know?
No response