How do I stop VS Code Draft 2020-12 schema warnings for mcp.json (Firecrawl MCP)?

Question

When I put Firecrawl MCP server config in mcp.json inside VS Code, the built-in JSON validator warns about unsupported Draft 2020-12 schema features. The MCP schema uses Draft 2020-12, which VS Code's built-in validator does not fully support. How can I get clean validation, IntelliSense, and autocomplete for mcp.json?

Originally asked on GitHub: https://github.com/firecrawl/firecrawl-mcp-server/issues/118

AgentArmor team · Accepted Answer

Status: the issue thread is open, but a workaround for VS Code's built-in Draft 2020-12 limitations is posted and one commenter confirmed it worked perfectly.

1. Install the JSON Schema Diagnostics extension from the VS Code marketplace: extension ID `prosser.json-schema-2020-validation`.

2. Add this to `.vscode/settings.json`:

```json
{
  "json.schemas": [
    {
      "fileMatch": ["**/mcp.json"],
      "url": "https://github.com/modelcontextprotocol/specification/raw/main/schema/mcp.json"
    }
  ],
  "json.validate.enable": false
}
```

`json.validate.enable: false` turns off the built-in validator so it stops producing false warnings; the extension handles validation instead.

3. In `mcp.json`, reference the same schema with `$schema` and define the Firecrawl server as a stdio server:

```json
{
  "$schema": "https://github.com/modelcontextprotocol/specification/raw/main/schema/mcp.json",
  "servers": {
    "firecrawl-mcp": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "firecrawl-mcp"],
      "env": {
        "FIRECRAWL_API_KEY": "YOUR_API_KEY"
      }
    }
  },
  "inputs": []
}
```

If IntelliSense does not appear after these changes, reload the VS Code window with "Developer: Reload Window". One commenter confirmed the steps remove the false warnings. Another commenter reported the extension works but can output its own errors, and linked extension issue #11 for that behavior.

Security note: `mcp.json` stores `FIRECRAWL_API_KEY` in plain text, so as general advice, do not commit it to source control.

AgentArmor team · Answer

**What a GitHub user tried on GitHub** (Outcome unclear)

The issue body proposed installing the JSON Schema Diagnostics extension, mapping **/mcp.json to the MCP schema URL in json.schemas, disabling the built-in validator with json.validate.enable: false, and adding $schema to mcp.json.

Source: https://github.com/firecrawl/firecrawl-mcp-server/issues/118

AgentArmor team · Answer

**What @jimfm tried on GitHub** (Worked)

A commenter reported that following the proposed steps worked perfectly as a workaround for the built-in validator warnings.

Source: https://github.com/firecrawl/firecrawl-mcp-server/issues/118#issuecomment-3368388403

AgentArmor team · Answer

**What @gmatt0 tried on GitHub** (Partly worked)

Another commenter said the extension works but also outputs its own errors, referencing extension issue #11 for the extra diagnostics.

Source: https://github.com/firecrawl/firecrawl-mcp-server/issues/118#issuecomment-3369071175

How do I stop VS Code Draft 2020-12 schema warnings for mcp.json (Firecrawl MCP)?

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How do I stop VS Code Draft 2020-12 schema warnings for mcp.json (Firecrawl MCP)?

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