MCP/schema: validation hardening + anchor-form $ref retention (PR #48638 series) #49978

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1. AceRothstein71 commented on Sep 19, 2026

   

   AceRothstein71

   on Sep 19, 2026

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   Cross-links: sibling tracking issues #49974 (perf/runtime), #49975 (shell classifier H-L), #49976 (shell classifier M-P), #49977 (instance lifecycle), #49978 (MCP/schema), #49979 (server/SSE + event/db), #49980 (updater tooling). Integration PR: #48638. Original tracker: #49565.
2. opencodejr commented on Oct 28, 2026

   

   opencodejrBot

   on Oct 28, 2026

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   Thanks for writing this up. As it stands, this reads as a plan for a fork's stacked PRs rather than a bug report we can reproduce. In your own words, could you briefly tell us:

   • Which OpenCode version you see this on (opencode --version). Does it happen on current v2, not only on your fork?
   • Which MCP server or tool schema triggers it. A minimal schema that shows the problem would help most (e.g. a resolvable anchor-form $ref that gets dropped, or a recursive schema that ends up with required: {}).
   • What you expected to happen and what happened instead, with the exact error from the provider or OpenCode, and the provider/model if it matters.

   You can reply here with the details or edit the issue. If you edit it, please also leave a comment saying you've updated it, so we know you're done editing.

   These existing issues look related, ordered from most to least likely. Please check whether one of them already covers your problem:

   • Console Go -> Meta: sanitize recursive $ref tool schemas (Codex Desktop codex_app tools hit it too) #48151: recursive $ref tool schemas need sanitizing before they reach the provider
   • Bug Report — houseCARL + Muse Spark 1.2 Contributor (Console Go) — Recursive JSON Schema #45823: tool calls fail with a recursive JSON Schema (Console Go)
   • Anthropic MCP tools fail when input schema uses root-level anyOf/oneOf/allOf #47543: MCP tools fail on Anthropic when the input schema uses root-level anyOf/oneOf/allOf
   • fix(core): keep MCP servers whose tool output schema has no type #57832: MCP servers dropped when a tool's output schema has no type
3. opencodejr

   added

   triaging

   on Oct 28, 2026
4. opencodejr

   closed this as not plannedon Oct 31, 2026
5. opencodejr commented on Oct 31, 2026

   

   opencodejrBot

   on Oct 31, 2026

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   We haven't heard back with the details we asked for: the OpenCode version, a specific MCP server or tool schema that triggers the problem, and the expected versus actual behaviour. Without them we can't reproduce this on v2, so I'm closing it for now.

   If you can share a minimal failing schema and the exact error you see on a current v2 release, please open a new issue using the Bug Report template. You can also check whether #48151, #45823, #47543 or #57832 already covers it. Thanks for looking into MCP schema handling.