[MCP] memory server tools fail to load: outputSchema uses JSON Schema draft-07, validator only supports 2020-12 #39908

Description

The MCP memory server (@modelcontextprotocol/server-memory) tools cannot be used. Every memory tool (search_nodes, create_entities, add_observations, etc.) fails with a schema validation error and is not registered.

Error

Tool 'search_nodes' has an invalid outputSchema: JSON Schema declares an unsupported dialect ("$schema": "http://json-schema.org/draft-07/schema#"). The default validator supports JSON Schema 2020-12 only; pass a pre-configured Ajv instance to AjvJs

Root cause

The official @modelcontextprotocol/server-memory generates its tool schemas with zod-to-json-schema, which by default stamps "$schema": "http://json-schema.org/draft-07/schema#". OpenCode's MCP client validates tool schemas with Ajv configured for JSON Schema 2020-12 only, so any server declaring an explicit draft-07 dialect is rejected before the tool is loaded.

The MCP spec (2025-11-25) honors the declared dialect when present (absent means 2020-12), so the validator should dispatch on the declared dialect instead of rejecting pre-wire. There is already a fix in the reference TypeScript SDK (modelcontextprotocol/typescript-sdk test outputSchemaDialect.test.ts) that does exactly this — the draft-07 Filesystem-server shape validates instead of failing pre-wire.

Environment

• OpenCode version: 1.18.8 (reported as latest)
• OS: Linux (Arch/Manjaro, X11)
• MCP server: @modelcontextprotocol/server-memory (npx latest)

Steps to reproduce

1. Add to opencode.json:

   "memory": {"type": "local", "command": ["npx", "-y", "@modelcontextprotocol/server-memory"], "enabled": true}

2. Start OpenCode.
3. Try to invoke any memory tool (e.g. search_nodes) or inspect the tool list.

Expected

Memory server tools load and validate correctly despite the draft-07 dialect declaration, mirroring the reference SDK behavior (dispatch on declared dialect).

Impact

The knowledge-graph memory feature is completely unusable in OpenCode. The graph data is still persisted on disk; only the tool interface fails.