fix: tools not loading on stdio server

[gregnr]

Problem

The docs Content API GraphQL response schema (used for the search_docs tool) used a discriminated union with z.undefined() to model success/error branches. There were 2 issues:

1. Zod v4 had a breaking change where z.undefined() on object properties requires the key to be explicitly present (and set as undefined). Absent keys failed validation, which broke tool loading
2. The union was actually incorrect from the beginning. The GraphQL spec allows both data and errors at the same time (partial results)

Fix

This PR replaces the union with a flat schema. data uses .nullish() because the spec allows it to be either absent (validation errors before execution) or null (resolver errors on non-nullable fields). errors uses .optional() since it's simply absent on success.

How to test

Configure Claude Code with the following MCP server config:

{
  "mcpServers": {
    "supabase-stdio": {
      "command": "npx",
      "args": [
        "-y",
        "@supabase/mcp-server-supabase@https://pkg.pr.new/supabase-community/supabase-mcp/@supabase/mcp-server-supabase@bbbe8ba"
      ],
      "env": {
        "SUPABASE_ACCESS_TOKEN": "<pat>"
      }
    }
  }
}

Run the claude CLI, enter /mcp, select supabase-stdio.

1. Confirm that the server connected successfully
2. Confirm that tools are available (by the presence of the View tools option, which displays all the tools when selected)

---

Resolves #261

[pkg-pr-new]

Open in StackBlitz

pnpm add https://pkg.pr.new/supabase-community/supabase-mcp/@supabase/mcp-server-postgrest@bbbe8ba

pnpm add https://pkg.pr.new/supabase-community/supabase-mcp/@supabase/mcp-server-supabase@bbbe8ba

pnpm add https://pkg.pr.new/supabase-community/supabase-mcp/@supabase/mcp-utils@bbbe8ba

commit: bbbe8ba

[mattrossman]

Preview build tested working on my end 👍