feat: support mcp_servers in config.toml

codex-rs/README.md

@@ -79,6 +79,38 @@ sandbox_permissions = [
 ]
 ```
 
+### mcp_servers
+
+Defines the list of MCP servers that Codex can consult for tool use. Currently, only servers that are launched by executing a program that communicate over stdio are supported. For servers that use the SSE transport, consider an adapter like [mcp-proxy](https://github.com/sparfenyuk/mcp-proxy).
+
+**Note:** Codex may cache the list of tools and resources from an MCP server so that Codex can include this information in context at startup without spawning all the servers. This is designed to save resources by loading MCP servers lazily.
+
+This config option is comparable to how Claude and Cursor define `mcpServers` in their respective JSON config files, though because Codex uses TOML for its config language, the format is slightly different. For example, the following config in JSON:
+
+```json
+{
+  "mcpServers": {
+    "server-name": {
+      "command": "npx",
+      "args": ["-y", "mcp-server"],
+      "env": {
+        "API_KEY": "value"
+      }
+    }
+  }
+}
+```
+
+Should be represented as follows in `~/.codex/config.toml`:
+
+```toml
+# IMPORTANT: the top-level key is `mcp_servers` rather than `mcpServers`.
+[mcp_servers.server-name]
+command = "npx"
+args = ["-y", "mcp-server"]
+env = { "API_KEY" = "value" }
+```
+
 ### disable_response_storage
 
 Currently, customers whose accounts are set to use Zero Data Retention (ZDR) must set `disable_response_storage` to `true` so that Codex uses an alternative to the Responses API that works with ZDR: