MCP for the TC39 specs (not affiliated with Ecma/TC39). SHA-pinned ECMA-262 + ECMA-402, AOID-aware search, cross-spec references, edition diffs, git history — read-only, deterministic, hosted-safe.
Setup
Choose your client, copy the config, then fill in any required environment variables.
Local
claude mcp add tc39 -- npx -y tc39-mcp~/.codex/config.toml
[mcp_servers.tc39]
command = "npx"
args = ["-y", "tc39-mcp"]
# codex mcp add tc39 -- npx -y tc39-mcp~/.cursor/mcp.json
{
"mcpServers": {
"tc39": {
"command": "npx",
"args": [
"-y",
"tc39-mcp"
]
}
}
}.vscode/mcp.json
{
"servers": {
"tc39": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"tc39-mcp"
]
}
}
}~/.gemini/settings.json
{
"mcpServers": {
"tc39": {
"command": "npx",
"args": [
"-y",
"tc39-mcp"
]
}
}
}claude_desktop_config.json
{
"mcpServers": {
"tc39": {
"command": "npx",
"args": [
"-y",
"tc39-mcp"
]
}
}
}.trae/mcp.json
{
"mcpServers": {
"tc39": {
"command": "npx",
"args": [
"-y",
"tc39-mcp"
]
}
}
}Remote
claude mcp add --transport http tc39 https://mcp.xyzzylabs.ai/tc39/mcp~/.codex/config.toml
[mcp_servers.tc39]
url = "https://mcp.xyzzylabs.ai/tc39/mcp"
# codex mcp add tc39 --url https://mcp.xyzzylabs.ai/tc39/mcp~/.cursor/mcp.json
{
"mcpServers": {
"tc39": {
"url": "https://mcp.xyzzylabs.ai/tc39/mcp"
}
}
}.vscode/mcp.json
{
"servers": {
"tc39": {
"type": "http",
"url": "https://mcp.xyzzylabs.ai/tc39/mcp"
}
}
}~/.gemini/settings.json
{
"mcpServers": {
"tc39": {
"httpUrl": "https://mcp.xyzzylabs.ai/tc39/mcp"
}
}
}claude_desktop_config.json · Customize › Connectors › Add custom connector
{
"mcpServers": {
"tc39": {
"command": "npx",
"args": [
"-y",
"mcp-remote",
"https://mcp.xyzzylabs.ai/tc39/mcp"
]
}
}
}.trae/mcp.json
{
"mcpServers": {
"tc39": {
"url": "https://mcp.xyzzylabs.ai/tc39/mcp"
}
}
}