Use env

codex-rs/Cargo.lock

@@ -992,7 +992,7 @@ dependencies = [
  "tokio-stream",
  "tracing",
  "tracing-subscriber",
- "unicode-width 0.1.14",
+ "unicode-width 0.2.1",
 ]
 
 [[package]]

codex-rs/cli/src/mcp_cmd.rs

@@ -1,4 +1,8 @@
 use std::collections::HashMap;
+use std::fs;
+use std::io::IsTerminal;
+use std::io::Read;
+use std::path::Path;
 
 use anyhow::Context;
 use anyhow::Result;
@@ -81,8 +85,28 @@ pub struct AddArgs {
     #[arg(long, value_parser = parse_env_pair, value_name = "KEY=VALUE")]
     pub env: Vec<(String, String)>,
 
+    /// URL for a streamable HTTP MCP server.
+    #[arg(long, value_name = "URL")]
+    pub url: Option<String>,
+
+    /// Optional environment variable to read for a bearer token.
+    #[arg(
+        long = "bearer-token-env-var",
+        value_name = "ENV_VAR",
+        requires = "url"
+    )]
+    pub bearer_token_env_var: Option<String>,
+
+    /// Read a bearer token for the HTTP server from stdin and persist it to ~/.codex/.env.
+    #[arg(
+        long = "with-bearer-token",
+        requires = "url",
+        help = "Read the MCP bearer token from stdin (e.g. `printenv GITHUB_API_KEY | codex mcp add github --url <URL> --with-bearer-token`)"
+    )]
+    pub with_bearer_token: bool,
+
     /// Command to launch the MCP server.
-    #[arg(trailing_var_arg = true, num_args = 1..)]
+    #[arg(trailing_var_arg = true, num_args = 0..)]
     pub command: Vec<String>,
 }
 
@@ -136,43 +160,87 @@ impl McpCli {
     }
 }
 
+const DEFAULT_BEARER_TOKEN_ENV_PREFIX: &str = "CODEX_MCP";
+
 async fn run_add(config_overrides: &CliConfigOverrides, add_args: AddArgs) -> Result<()> {
     // Validate any provided overrides even though they are not currently applied.
     config_overrides.parse_overrides().map_err(|e| anyhow!(e))?;
 
-    let AddArgs { name, env, command } = add_args;
+    let AddArgs {
+        name,
+        env,
+        url,
+        bearer_token_env_var,
+        with_bearer_token,
+        command,
+    } = add_args;
 
     validate_server_name(&name)?;
 
-    let mut command_parts = command.into_iter();
-    let command_bin = command_parts
-        .next()
-        .ok_or_else(|| anyhow!("command is required"))?;
-    let command_args: Vec<String> = command_parts.collect();
-
-    let env_map = if env.is_empty() {
-        None
-    } else {
-        let mut map = HashMap::new();
-        for (key, value) in env {
-            map.insert(key, value);
-        }
-        Some(map)
-    };
-
     let codex_home = find_codex_home().context("failed to resolve CODEX_HOME")?;
     let mut servers = load_global_mcp_servers(&codex_home)
         .await
         .with_context(|| format!("failed to load MCP servers from {}", codex_home.display()))?;
 
-    let new_entry = McpServerConfig {
-        transport: McpServerTransportConfig::Stdio {
-            command: command_bin,
-            args: command_args,
-            env: env_map,
-        },
-        startup_timeout_sec: None,
-        tool_timeout_sec: None,
+    let new_entry = if let Some(url) = url {
+        if !env.is_empty() {
+            bail!("--env is not supported when adding a streamable HTTP server");
+        }
+        if !command.is_empty() {
+            bail!("command arguments are not supported when --url is provided");
+        }
+
+        let mut env_var_name = bearer_token_env_var;
+        if with_bearer_token {
+            let token = read_bearer_token_from_stdin()?;
+            let key = env_var_name
+                .take()
+                .unwrap_or_else(|| derive_bearer_token_env_var(&name));
+            persist_env_var(&codex_home, &key, &token)?;
+            env_var_name = Some(key);
+        }
+
+        McpServerConfig {
+            transport: McpServerTransportConfig::StreamableHttp {
+                url,
+                bearer_token_env_var: env_var_name,
+            },
+            startup_timeout_sec: None,
+            tool_timeout_sec: None,
+        }
+    } else {
+        if with_bearer_token {
+            bail!("--with-bearer-token can only be used with --url");
+        }
+        if bearer_token_env_var.is_some() {
+            bail!("--bearer-token-env-var can only be used with --url");
+        }
+
+        let mut command_parts = command.into_iter();
+        let command_bin = command_parts
+            .next()
+            .ok_or_else(|| anyhow!("command is required"))?;
+        let command_args: Vec<String> = command_parts.collect();
+
+        let env_map = if env.is_empty() {
+            None
+        } else {
+            let mut map = HashMap::new();
+            for (key, value) in env {
+                map.insert(key, value);
+            }
+            Some(map)
+        };
+
+        McpServerConfig {
+            transport: McpServerTransportConfig::Stdio {
+                command: command_bin,
+                args: command_args,
+                env: env_map,
+            },
+            startup_timeout_sec: None,
+            tool_timeout_sec: None,
+        }
     };
 
     servers.insert(name.clone(), new_entry);
@@ -288,11 +356,14 @@ async fn run_list(config_overrides: &CliConfigOverrides, list_args: ListArgs) ->
                         "args": args,
                         "env": env,
                     }),
-                    McpServerTransportConfig::StreamableHttp { url, bearer_token } => {
+                    McpServerTransportConfig::StreamableHttp {
+                        url,
+                        bearer_token_env_var,
+                    } => {
                         serde_json::json!({
                             "type": "streamable_http",
                             "url": url,
-                            "bearer_token": bearer_token,
+                            "bearer_token_env_var": bearer_token_env_var,
                         })
                     }
                 };
@@ -345,13 +416,15 @@ async fn run_list(config_overrides: &CliConfigOverrides, list_args: ListArgs) ->
                 };
                 stdio_rows.push([name.clone(), command.clone(), args_display, env_display]);
             }
-            McpServerTransportConfig::StreamableHttp { url, bearer_token } => {
-                let has_bearer = if bearer_token.is_some() {
-                    "True"
-                } else {
-                    "False"
-                };
-                http_rows.push([name.clone(), url.clone(), has_bearer.into()]);
+            McpServerTransportConfig::StreamableHttp {
+                url,
+                bearer_token_env_var,
+            } => {
+                http_rows.push([
+                    name.clone(),
+                    url.clone(),
+                    bearer_token_env_var.clone().unwrap_or("-".to_string()),
+                ]);
             }
         }
     }
@@ -396,7 +469,7 @@ async fn run_list(config_overrides: &CliConfigOverrides, list_args: ListArgs) ->
     }
 
     if !http_rows.is_empty() {
-        let mut widths = ["Name".len(), "Url".len(), "Has Bearer Token".len()];
+        let mut widths = ["Name".len(), "Url".len(), "Bearer Token Env Var".len()];
         for row in &http_rows {
             for (i, cell) in row.iter().enumerate() {
                 widths[i] = widths[i].max(cell.len());
@@ -407,7 +480,7 @@ async fn run_list(config_overrides: &CliConfigOverrides, list_args: ListArgs) ->
             "{:<name_w$}  {:<url_w$}  {:<token_w$}",
             "Name",
             "Url",
-            "Has Bearer Token",
+            "Bearer Token Env Var",
             name_w = widths[0],
             url_w = widths[1],
             token_w = widths[2],
@@ -447,10 +520,13 @@ async fn run_get(config_overrides: &CliConfigOverrides, get_args: GetArgs) -> Re
                 "args": args,
                 "env": env,
             }),
-            McpServerTransportConfig::StreamableHttp { url, bearer_token } => serde_json::json!({
+            McpServerTransportConfig::StreamableHttp {
+                url,
+                bearer_token_env_var,
+            } => serde_json::json!({
                 "type": "streamable_http",
                 "url": url,
-                "bearer_token": bearer_token,
+                "bearer_token_env_var": bearer_token_env_var,
             }),
         };
         let output = serde_json::to_string_pretty(&serde_json::json!({
@@ -493,11 +569,14 @@ async fn run_get(config_overrides: &CliConfigOverrides, get_args: GetArgs) -> Re
             };
             println!("  env: {env_display}");
         }
-        McpServerTransportConfig::StreamableHttp { url, bearer_token } => {
+        McpServerTransportConfig::StreamableHttp {
+            url,
+            bearer_token_env_var,
+        } => {
             println!("  transport: streamable_http");
             println!("  url: {url}");
-            let bearer = bearer_token.as_deref().unwrap_or("-");
-            println!("  bearer_token: {bearer}");
+            let env_var = bearer_token_env_var.as_deref().unwrap_or("-");
+            println!("  bearer_token_env_var: {env_var}");
         }
     }
     if let Some(timeout) = server.startup_timeout_sec {
@@ -538,3 +617,87 @@ fn validate_server_name(name: &str) -> Result<()> {
         bail!("invalid server name '{name}' (use letters, numbers, '-', '_')");
     }
 }
+
+fn read_bearer_token_from_stdin() -> Result<String> {
+    let mut stdin = std::io::stdin();
+    if stdin.is_terminal() {
+        bail!(
+            "--with-bearer-token expects the bearer token on stdin. Try piping it, e.g. `printenv GITHUB_API_KEY | codex mcp add <name> --url <url> --with-bearer-token`."
+        );
+    }
+
+    eprintln!("Reading MCP bearer token from stdin...");
+    let mut buffer = String::new();
+    stdin
+        .read_to_string(&mut buffer)
+        .context("failed to read bearer token from stdin")?;
+    let token = buffer.trim().to_string();
+    if token.is_empty() {
+        bail!("No bearer token provided via stdin.");
+    }
+
+    Ok(token)
+}
+
+fn derive_bearer_token_env_var(server_name: &str) -> String {
+    let mut normalized = String::new();
+    for ch in server_name.chars() {
+        if ch.is_ascii_alphanumeric() {
+            normalized.push(ch.to_ascii_uppercase());
+        } else {
+            normalized.push('_');
+        }
+    }
+    format!("{DEFAULT_BEARER_TOKEN_ENV_PREFIX}_{normalized}_BEARER_TOKEN")
+}
+
+fn persist_env_var(codex_home: &Path, key: &str, value: &str) -> Result<()> {
+    let dotenv_path = codex_home.join(".env");
+    if let Some(parent) = dotenv_path.parent() {
+        fs::create_dir_all(parent)
+            .with_context(|| format!("failed to create directory {}", parent.display()))?;
+    }
+
+    let mut lines = Vec::new();
+    let mut replaced = false;
+    if let Ok(existing) = fs::read_to_string(&dotenv_path) {
+        for raw_line in existing.lines() {
+            if let Some((existing_key, had_export)) = parse_env_key(raw_line)
+                && existing_key == key
+            {
+                let prefix = if had_export { "export " } else { "" };
+                lines.push(format!("{prefix}{key}={value}"));
+                replaced = true;
+                continue;
+            }
+            lines.push(raw_line.to_string());
+        }
+    }
+
+    if !replaced {
+        lines.push(format!("{key}={value}"));
+    }
+
+    let mut contents = lines.join("\n");
+    if !contents.ends_with('\n') {
+        contents.push('\n');
+    }
+
+    fs::write(&dotenv_path, contents)
+        .with_context(|| format!("failed to update {}", dotenv_path.display()))?;
+    Ok(())
+}
+
+fn parse_env_key(line: &str) -> Option<(String, bool)> {
+    let trimmed = line.trim();
+    if trimmed.is_empty() || trimmed.starts_with('#') {
+        return None;
+    }
+    let (trimmed, had_export) = if let Some(stripped) = trimmed.strip_prefix("export ") {
+        (stripped, true)
+    } else {
+        (trimmed, false)
+    };
+    let (key, _) = trimmed.split_once('=')?;
+    Some((key.trim().to_string(), had_export))
+}

codex-rs/cli/tests/mcp_add_remove.rs

@@ -1,3 +1,4 @@
+use std::fs;
 use std::path::Path;
 
 use anyhow::Result;
@@ -93,3 +94,107 @@ async fn add_with_env_preserves_key_order_and_values() -> Result<()> {
 
     Ok(())
 }
+
+#[tokio::test]
+async fn add_streamable_http_with_bearer_token_env_var() -> Result<()> {
+    let codex_home = TempDir::new()?;
+    let dotenv_path = codex_home.path().join(".env");
+
+    let mut add_cmd = codex_command(codex_home.path())?;
+    add_cmd
+        .write_stdin("super-secret-token")
+        .args([
+            "mcp",
+            "add",
+            "github",
+            "--url",
+            "https://example.com/mcp",
+            "--with-bearer-token",
+        ])
+        .assert()
+        .success();
+
+    let servers = load_global_mcp_servers(codex_home.path()).await?;
+    let github = servers.get("github").expect("github server should exist");
+    match &github.transport {
+        McpServerTransportConfig::StreamableHttp {
+            url,
+            bearer_token_env_var,
+        } => {
+            assert_eq!(url, "https://example.com/mcp");
+            assert_eq!(
+                bearer_token_env_var.as_deref(),
+                Some("CODEX_MCP_GITHUB_BEARER_TOKEN")
+            );
+        }
+        other => panic!("unexpected transport: {other:?}"),
+    }
+
+    let dotenv_contents = fs::read_to_string(&dotenv_path)?;
+    assert!(dotenv_contents.contains("CODEX_MCP_GITHUB_BEARER_TOKEN=super-secret-token"));
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn add_streamable_http_with_custom_env_var() -> Result<()> {
+    let codex_home = TempDir::new()?;
+
+    let mut add_cmd = codex_command(codex_home.path())?;
+    add_cmd
+        .write_stdin("another-secret")
+        .args([
+            "mcp",
+            "add",
+            "issues",
+            "--url",
+            "https://example.com/issues",
+            "--bearer-token-env-var",
+            "GITHUB_TOKEN",
+            "--with-bearer-token",
+        ])
+        .assert()
+        .success();
+
+    let servers = load_global_mcp_servers(codex_home.path()).await?;
+    let issues = servers.get("issues").expect("issues server should exist");
+    match &issues.transport {
+        McpServerTransportConfig::StreamableHttp {
+            url,
+            bearer_token_env_var,
+        } => {
+            assert_eq!(url, "https://example.com/issues");
+            assert_eq!(bearer_token_env_var.as_deref(), Some("GITHUB_TOKEN"));
+        }
+        other => panic!("unexpected transport: {other:?}"),
+    }
+
+    let dotenv_contents = fs::read_to_string(codex_home.path().join(".env"))?;
+    assert!(dotenv_contents.contains("GITHUB_TOKEN=another-secret"));
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn add_streamable_http_with_bearer_token_requires_stdin() -> Result<()> {
+    let codex_home = TempDir::new()?;
+
+    let mut add_cmd = codex_command(codex_home.path())?;
+    add_cmd
+        .args([
+            "mcp",
+            "add",
+            "github",
+            "--url",
+            "https://example.com/mcp",
+            "--with-bearer-token",
+        ])
+        .assert()
+        .failure()
+        .stderr(contains("No bearer token provided via stdin."));
+
+    let servers = load_global_mcp_servers(codex_home.path()).await?;
+    assert!(servers.is_empty());
+
+    Ok(())
+}

codex-rs/core/src/config.rs

@@ -37,8 +37,10 @@ use dirs::home_dir;
 use serde::Deserialize;
 use std::collections::BTreeMap;
 use std::collections::HashMap;
+use std::io::ErrorKind;
 use std::path::Path;
 use std::path::PathBuf;
+
 use tempfile::NamedTempFile;
 use toml::Value as TomlValue;
 use toml_edit::Array as TomlArray;
@@ -301,12 +303,35 @@ pub async fn load_global_mcp_servers(
         return Ok(BTreeMap::new());
     };
 
+    ensure_no_inline_bearer_tokens(servers_value)?;
+
     servers_value
         .clone()
         .try_into()
         .map_err(|e| std::io::Error::new(std::io::ErrorKind::InvalidData, e))
 }
 
+/// We briefly allowed plain text bearer_token fields in MCP server configs.
+/// We want to warn people who recently added these fields but can remove this after a few months.
+fn ensure_no_inline_bearer_tokens(value: &TomlValue) -> std::io::Result<()> {
+    let Some(servers_table) = value.as_table() else {
+        return Ok(());
+    };
+
+    for (server_name, server_value) in servers_table {
+        if let Some(server_table) = server_value.as_table()
+            && server_table.contains_key("bearer_token")
+        {
+            let message = format!(
+                "mcp_servers.{server_name} uses unsupported `bearer_token`; set `bearer_token_env_var` or rerun `codex mcp add {server_name} --with-bearer-token`."
+            );
+            return Err(std::io::Error::new(ErrorKind::InvalidData, message));
+        }
+    }
+
+    Ok(())
+}
+
 pub fn write_global_mcp_servers(
     codex_home: &Path,
     servers: &BTreeMap<String, McpServerConfig>,
@@ -355,10 +380,13 @@ pub fn write_global_mcp_servers(
                         entry["env"] = TomlItem::Table(env_table);
                     }
                 }
-                McpServerTransportConfig::StreamableHttp { url, bearer_token } => {
+                McpServerTransportConfig::StreamableHttp {
+                    url,
+                    bearer_token_env_var,
+                } => {
                     entry["url"] = toml_edit::value(url.clone());
-                    if let Some(token) = bearer_token {
-                        entry["bearer_token"] = toml_edit::value(token.clone());
+                    if let Some(env_var) = bearer_token_env_var {
+                        entry["bearer_token_env_var"] = toml_edit::value(env_var.clone());
                     }
                 }
             }
@@ -1471,6 +1499,31 @@ startup_timeout_ms = 2500
         Ok(())
     }
 
+    #[tokio::test]
+    async fn load_global_mcp_servers_rejects_inline_bearer_token() -> anyhow::Result<()> {
+        let codex_home = TempDir::new()?;
+        let config_path = codex_home.path().join(CONFIG_TOML_FILE);
+
+        std::fs::write(
+            &config_path,
+            r#"
+[mcp_servers.docs]
+url = "https://example.com/mcp"
+bearer_token = "secret"
+"#,
+        )?;
+
+        let err = load_global_mcp_servers(codex_home.path())
+            .await
+            .expect_err("bearer_token entries should be rejected");
+
+        assert_eq!(err.kind(), std::io::ErrorKind::InvalidData);
+        assert!(err.to_string().contains("bearer_token"));
+        assert!(err.to_string().contains("bearer_token_env_var"));
+
+        Ok(())
+    }
+
     #[tokio::test]
     async fn write_global_mcp_servers_serializes_env_sorted() -> anyhow::Result<()> {
         let codex_home = TempDir::new()?;
@@ -1534,7 +1587,7 @@ ZIG_VAR = "3"
             McpServerConfig {
                 transport: McpServerTransportConfig::StreamableHttp {
                     url: "https://example.com/mcp".to_string(),
-                    bearer_token: Some("secret-token".to_string()),
+                    bearer_token_env_var: Some("MCP_TOKEN".to_string()),
                 },
                 startup_timeout_sec: Some(Duration::from_secs(2)),
                 tool_timeout_sec: None,
@@ -1549,7 +1602,7 @@ ZIG_VAR = "3"
             serialized,
             r#"[mcp_servers.docs]
 url = "https://example.com/mcp"
-bearer_token = "secret-token"
+bearer_token_env_var = "MCP_TOKEN"
 startup_timeout_sec = 2.0
 "#
         );
@@ -1557,9 +1610,12 @@ startup_timeout_sec = 2.0
         let loaded = load_global_mcp_servers(codex_home.path()).await?;
         let docs = loaded.get("docs").expect("docs entry");
         match &docs.transport {
-            McpServerTransportConfig::StreamableHttp { url, bearer_token } => {
+            McpServerTransportConfig::StreamableHttp {
+                url,
+                bearer_token_env_var,
+            } => {
                 assert_eq!(url, "https://example.com/mcp");
-                assert_eq!(bearer_token.as_deref(), Some("secret-token"));
+                assert_eq!(bearer_token_env_var.as_deref(), Some("MCP_TOKEN"));
             }
             other => panic!("unexpected transport {other:?}"),
         }
@@ -1570,7 +1626,7 @@ startup_timeout_sec = 2.0
             McpServerConfig {
                 transport: McpServerTransportConfig::StreamableHttp {
                     url: "https://example.com/mcp".to_string(),
-                    bearer_token: None,
+                    bearer_token_env_var: None,
                 },
                 startup_timeout_sec: None,
                 tool_timeout_sec: None,
@@ -1589,9 +1645,12 @@ url = "https://example.com/mcp"
         let loaded = load_global_mcp_servers(codex_home.path()).await?;
         let docs = loaded.get("docs").expect("docs entry");
         match &docs.transport {
-            McpServerTransportConfig::StreamableHttp { url, bearer_token } => {
+            McpServerTransportConfig::StreamableHttp {
+                url,
+                bearer_token_env_var,
+            } => {
                 assert_eq!(url, "https://example.com/mcp");
-                assert!(bearer_token.is_none());
+                assert!(bearer_token_env_var.is_none());
             }
             other => panic!("unexpected transport {other:?}"),
         }

codex-rs/core/src/config_types.rs

@@ -48,6 +48,7 @@ impl<'de> Deserialize<'de> for McpServerConfig {
 
             url: Option<String>,
             bearer_token: Option<String>,
+            bearer_token_env_var: Option<String>,
 
             #[serde(default)]
             startup_timeout_sec: Option<f64>,
@@ -80,6 +81,19 @@ impl<'de> Deserialize<'de> for McpServerConfig {
             )))
         }
 
+        fn throw_if_bearer_token_set<E>(transport: &str, value: Option<&String>) -> Result<(), E>
+        where
+            E: SerdeError,
+        {
+            if value.is_none() {
+                return Ok(());
+            }
+
+            Err(E::custom(format!(
+                "bearer_token is not supported for {transport}; set bearer_token_env_var or use `codex mcp add <name> --url <url> --with-bearer-token`",
+            )))
+        }
+
         let transport = match raw {
             RawMcpServerConfig {
                 command: Some(command),
@@ -87,10 +101,16 @@ impl<'de> Deserialize<'de> for McpServerConfig {
                 env,
                 url,
                 bearer_token,
+                bearer_token_env_var,
                 ..
             } => {
                 throw_if_set("stdio", "url", url.as_ref())?;
-                throw_if_set("stdio", "bearer_token", bearer_token.as_ref())?;
+                throw_if_bearer_token_set("stdio", bearer_token.as_ref())?;
+                throw_if_set(
+                    "stdio",
+                    "bearer_token_env_var",
+                    bearer_token_env_var.as_ref(),
+                )?;
                 McpServerTransportConfig::Stdio {
                     command,
                     args: args.unwrap_or_default(),
@@ -100,6 +120,7 @@ impl<'de> Deserialize<'de> for McpServerConfig {
             RawMcpServerConfig {
                 url: Some(url),
                 bearer_token,
+                bearer_token_env_var,
                 command,
                 args,
                 env,
@@ -108,7 +129,11 @@ impl<'de> Deserialize<'de> for McpServerConfig {
                 throw_if_set("streamable_http", "command", command.as_ref())?;
                 throw_if_set("streamable_http", "args", args.as_ref())?;
                 throw_if_set("streamable_http", "env", env.as_ref())?;
-                McpServerTransportConfig::StreamableHttp { url, bearer_token }
+                throw_if_bearer_token_set("streamable_http", bearer_token.as_ref())?;
+                McpServerTransportConfig::StreamableHttp {
+                    url,
+                    bearer_token_env_var,
+                }
             }
             _ => return Err(SerdeError::custom("invalid transport")),
         };
@@ -135,11 +160,11 @@ pub enum McpServerTransportConfig {
     /// https://modelcontextprotocol.io/specification/2025-06-18/basic/transports#streamable-http
     StreamableHttp {
         url: String,
-        /// A plain text bearer token to use for authentication.
-        /// This bearer token will be included in the HTTP request header as an `Authorization: Bearer <token>` header.
-        /// This should be used with caution because it lives on disk in clear text.
+        /// Name of the environment variable to read for an HTTP bearer token.
+        /// When set, requests will include the token via `Authorization: Bearer <token>`.
+        /// The actual secret value must be provided via the environment.
         #[serde(default, skip_serializing_if = "Option::is_none")]
-        bearer_token: Option<String>,
+        bearer_token_env_var: Option<String>,
     },
 }
 
@@ -506,17 +531,17 @@ mod tests {
             cfg.transport,
             McpServerTransportConfig::StreamableHttp {
                 url: "https://example.com/mcp".to_string(),
-                bearer_token: None
+                bearer_token_env_var: None
             }
         );
     }
 
     #[test]
-    fn deserialize_streamable_http_server_config_with_bearer_token() {
+    fn deserialize_streamable_http_server_config_with_env_var() {
         let cfg: McpServerConfig = toml::from_str(
             r#"
             url = "https://example.com/mcp"
-            bearer_token = "secret"
+            bearer_token_env_var = "GITHUB_TOKEN"
         "#,
         )
         .expect("should deserialize http config");
@@ -525,7 +550,7 @@ mod tests {
             cfg.transport,
             McpServerTransportConfig::StreamableHttp {
                 url: "https://example.com/mcp".to_string(),
-                bearer_token: Some("secret".to_string())
+                bearer_token_env_var: Some("GITHUB_TOKEN".to_string())
             }
         );
     }
@@ -553,13 +578,18 @@ mod tests {
     }
 
     #[test]
-    fn deserialize_rejects_bearer_token_for_stdio_transport() {
-        toml::from_str::<McpServerConfig>(
+    fn deserialize_rejects_inline_bearer_token_field() {
+        let err = toml::from_str::<McpServerConfig>(
             r#"
-            command = "echo"
+            url = "https://example.com"
             bearer_token = "secret"
         "#,
         )
-        .expect_err("should reject bearer token for stdio transport");
+        .expect_err("should reject bearer_token field");
+
+        assert!(
+            err.to_string().contains("bearer_token is not supported"),
+            "unexpected error: {err}"
+        );
     }
 }

codex-rs/core/src/mcp_connection_manager.rs

@@ -8,6 +8,7 @@
 
 use std::collections::HashMap;
 use std::collections::HashSet;
+use std::env;
 use std::ffi::OsString;
 use std::sync::Arc;
 use std::time::Duration;
@@ -205,6 +206,14 @@ impl McpConnectionManager {
             let startup_timeout = cfg.startup_timeout_sec.unwrap_or(DEFAULT_STARTUP_TIMEOUT);
             let tool_timeout = cfg.tool_timeout_sec.unwrap_or(DEFAULT_TOOL_TIMEOUT);
 
+            let resolved_bearer_token = match &cfg.transport {
+                McpServerTransportConfig::StreamableHttp {
+                    bearer_token_env_var,
+                    ..
+                } => resolve_bearer_token(&server_name, bearer_token_env_var.as_deref())?,
+                _ => None,
+            };
+
             join_set.spawn(async move {
                 let McpServerConfig { transport, .. } = cfg;
                 let params = mcp_types::InitializeRequestParams {
@@ -242,11 +251,11 @@ impl McpConnectionManager {
                         )
                         .await
                     }
-                    McpServerTransportConfig::StreamableHttp { url, bearer_token } => {
+                    McpServerTransportConfig::StreamableHttp { url, .. } => {
                         McpClientAdapter::new_streamable_http_client(
                             server_name.clone(),
                             url,
-                            bearer_token,
+                            resolved_bearer_token,
                             params,
                             startup_timeout,
                         )
@@ -336,6 +345,33 @@ impl McpConnectionManager {
     }
 }
 
+fn resolve_bearer_token(
+    server_name: &str,
+    bearer_token_env_var: Option<&str>,
+) -> Result<Option<String>> {
+    let Some(env_var) = bearer_token_env_var else {
+        return Ok(None);
+    };
+
+    match env::var(env_var) {
+        Ok(value) => {
+            if value.is_empty() {
+                Err(anyhow!(
+                    "Environment variable {env_var} for MCP server '{server_name}' is empty"
+                ))
+            } else {
+                Ok(Some(value))
+            }
+        }
+        Err(env::VarError::NotPresent) => Err(anyhow!(
+            "Environment variable {env_var} for MCP server '{server_name}' is not set"
+        )),
+        Err(env::VarError::NotUnicode(_)) => Err(anyhow!(
+            "Environment variable {env_var} for MCP server '{server_name}' contains invalid Unicode"
+        )),
+    }
+}
+
 /// Query every server for its available tools and return a single map that
 /// contains **all** tools. Each key is the fully-qualified name for the tool.
 async fn list_all_tools(clients: &HashMap<String, ManagedClient>) -> Result<Vec<ToolInfo>> {

codex-rs/core/tests/suite/rmcp_client.rs

@@ -232,7 +232,7 @@ async fn streamable_http_tool_call_round_trip() -> anyhow::Result<()> {
                 McpServerConfig {
                     transport: McpServerTransportConfig::StreamableHttp {
                         url: server_url,
-                        bearer_token: None,
+                        bearer_token_env_var: None,
                     },
                     startup_timeout_sec: Some(Duration::from_secs(10)),
                     tool_timeout_sec: None,
@@ -412,7 +412,7 @@ async fn streamable_http_with_oauth_round_trip() -> anyhow::Result<()> {
                 McpServerConfig {
                     transport: McpServerTransportConfig::StreamableHttp {
                         url: server_url,
-                        bearer_token: None,
+                        bearer_token_env_var: None,
                     },
                     startup_timeout_sec: Some(Duration::from_secs(10)),
                     tool_timeout_sec: None,