Struct ExternalToolConfig 

pub struct ExternalToolConfig {

    pub id: String,
    pub transport: ExternalToolTransport,
    pub command: Vec<String>,
    pub url: Option<String>,
    pub env_from_env: BTreeMap<String, String>,
    pub headers_from_env: BTreeMap<String, String>,
    pub timeout_ms: u64,
    pub max_result_bytes: usize,
    pub max_stderr_bytes: usize,
    pub modes: Vec<ExternalToolMode>,
    pub roots: Vec<McpRootConfig>,
    pub sampling: bool,
    pub elicitation: bool,
    pub subscriptions: bool,
    pub resource_subscriptions: Vec<String>,
    pub tasks: bool,
    pub max_task_wait_ms: u64,
    pub max_sampling_tokens: u32,
    pub tools: BTreeMap<String, ExternalToolPolicy>,
}

One [[external_tools]] server. Secret values are never stored here: environment maps contain destination/header names and source variable names.

Fields

id: String

transport: ExternalToolTransport

command: Vec<String>

Direct argv. Element zero is the program; no shell parsing occurs.

url: Option<String>

env_from_env: BTreeMap<String, String>

Child variable -> source environment variable, for stdio servers.

headers_from_env: BTreeMap<String, String>

HTTP header -> source environment variable.

timeout_ms: u64

max_result_bytes: usize

max_stderr_bytes: usize

modes: Vec<ExternalToolMode>

roots: Vec<McpRootConfig>

Explicit roots returned to server-initiated roots/list requests. An empty list means that the roots capability is not advertised.

sampling: bool

Allow server-initiated model sampling. This is opt-in because it spends the configured provider’s model budget.

elicitation: bool

Allow server-initiated elicitation. A product surface must also install an interactive handler; otherwise connection fails closed.

subscriptions: bool

Open the MCP 2026-07-28 subscriptions/listen stream for advertised list-change notifications and the resource URIs below.

resource_subscriptions: Vec<String>

tasks: bool

Advertise and drive the official tasks extension for long-running calls.

max_task_wait_ms: u64

Overall deadline for one asynchronous MCP task, across every poll and input-required round. Individual requests still use timeout_ms.

max_sampling_tokens: u32

Local upper bound on a server sampling request.

tools: BTreeMap<String, ExternalToolPolicy>

Implementations

impl ExternalToolConfig

pub fn supports(&self, mode: ExternalToolMode) -> bool

Trait Implementations

impl Clone for ExternalToolConfig

fn clone(&self) -> ExternalToolConfig

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ExternalToolConfig

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for ExternalToolConfig

fn default() -> Self

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for ExternalToolConfig

where ExternalToolConfig: Default,

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for ExternalToolConfig

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.