fcd197d596
Apparently `std::env::args()` will panic during iteration if any argument to the process is not valid Unicode: https://doc.rust-lang.org/std/env/fn.args.html Let's avoid the risk and just go with `std::env::args_os()`. --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/openai/codex/pull/1698). * #1705 * #1703 * #1702 * __->__ #1698 * #1697
371 lines
12 KiB
Rust
371 lines
12 KiB
Rust
//! Connection manager for Model Context Protocol (MCP) servers.
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//!
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//! The [`McpConnectionManager`] owns one [`codex_mcp_client::McpClient`] per
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//! configured server (keyed by the *server name*). It offers convenience
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//! helpers to query the available tools across *all* servers and returns them
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//! in a single aggregated map using the fully-qualified tool name
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//! `"<server><MCP_TOOL_NAME_DELIMITER><tool>"` as the key.
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use std::collections::HashMap;
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use std::collections::HashSet;
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use std::ffi::OsString;
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use std::time::Duration;
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use anyhow::Context;
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use anyhow::Result;
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use anyhow::anyhow;
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use codex_mcp_client::McpClient;
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use mcp_types::ClientCapabilities;
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use mcp_types::Implementation;
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use mcp_types::Tool;
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use serde_json::json;
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use sha1::Digest;
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use sha1::Sha1;
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use tokio::task::JoinSet;
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use tracing::info;
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use tracing::warn;
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use crate::config_types::McpServerConfig;
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/// Delimiter used to separate the server name from the tool name in a fully
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/// qualified tool name.
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///
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/// OpenAI requires tool names to conform to `^[a-zA-Z0-9_-]+$`, so we must
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/// choose a delimiter from this character set.
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const MCP_TOOL_NAME_DELIMITER: &str = "__";
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const MAX_TOOL_NAME_LENGTH: usize = 64;
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/// Timeout for the `tools/list` request.
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const LIST_TOOLS_TIMEOUT: Duration = Duration::from_secs(10);
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/// Map that holds a startup error for every MCP server that could **not** be
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/// spawned successfully.
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pub type ClientStartErrors = HashMap<String, anyhow::Error>;
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fn qualify_tools(tools: Vec<ToolInfo>) -> HashMap<String, ToolInfo> {
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let mut used_names = HashSet::new();
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let mut qualified_tools = HashMap::new();
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for tool in tools {
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let mut qualified_name = format!(
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"{}{}{}",
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tool.server_name, MCP_TOOL_NAME_DELIMITER, tool.tool_name
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);
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if qualified_name.len() > MAX_TOOL_NAME_LENGTH {
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let mut hasher = Sha1::new();
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hasher.update(qualified_name.as_bytes());
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let sha1 = hasher.finalize();
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let sha1_str = format!("{sha1:x}");
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// Truncate to make room for the hash suffix
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let prefix_len = MAX_TOOL_NAME_LENGTH - sha1_str.len();
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qualified_name = format!("{}{}", &qualified_name[..prefix_len], sha1_str);
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}
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if used_names.contains(&qualified_name) {
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warn!("skipping duplicated tool {}", qualified_name);
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continue;
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}
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used_names.insert(qualified_name.clone());
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qualified_tools.insert(qualified_name, tool);
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}
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qualified_tools
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}
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struct ToolInfo {
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server_name: String,
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tool_name: String,
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tool: Tool,
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}
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/// A thin wrapper around a set of running [`McpClient`] instances.
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#[derive(Default)]
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pub(crate) struct McpConnectionManager {
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/// Server-name -> client instance.
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///
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/// The server name originates from the keys of the `mcp_servers` map in
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/// the user configuration.
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clients: HashMap<String, std::sync::Arc<McpClient>>,
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/// Fully qualified tool name -> tool instance.
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tools: HashMap<String, ToolInfo>,
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}
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impl McpConnectionManager {
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/// Spawn a [`McpClient`] for each configured server.
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///
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/// * `mcp_servers` – Map loaded from the user configuration where *keys*
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/// are human-readable server identifiers and *values* are the spawn
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/// instructions.
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///
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/// Servers that fail to start are reported in `ClientStartErrors`: the
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/// user should be informed about these errors.
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pub async fn new(
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mcp_servers: HashMap<String, McpServerConfig>,
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) -> Result<(Self, ClientStartErrors)> {
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// Early exit if no servers are configured.
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if mcp_servers.is_empty() {
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return Ok((Self::default(), ClientStartErrors::default()));
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}
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// Launch all configured servers concurrently.
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let mut join_set = JoinSet::new();
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let mut errors = ClientStartErrors::new();
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for (server_name, cfg) in mcp_servers {
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// Validate server name before spawning
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if !is_valid_mcp_server_name(&server_name) {
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let error = anyhow::anyhow!(
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"invalid server name '{}': must match pattern ^[a-zA-Z0-9_-]+$",
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server_name
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);
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errors.insert(server_name, error);
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continue;
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}
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join_set.spawn(async move {
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let McpServerConfig { command, args, env } = cfg;
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let client_res = McpClient::new_stdio_client(
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command.into(),
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args.into_iter().map(OsString::from).collect(),
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env,
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)
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.await;
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match client_res {
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Ok(client) => {
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// Initialize the client.
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let params = mcp_types::InitializeRequestParams {
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capabilities: ClientCapabilities {
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experimental: None,
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roots: None,
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sampling: None,
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// https://modelcontextprotocol.io/specification/2025-06-18/client/elicitation#capabilities
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// indicates this should be an empty object.
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elicitation: Some(json!({})),
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},
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client_info: Implementation {
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name: "codex-mcp-client".to_owned(),
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version: env!("CARGO_PKG_VERSION").to_owned(),
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title: Some("Codex".into()),
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},
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protocol_version: mcp_types::MCP_SCHEMA_VERSION.to_owned(),
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};
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let initialize_notification_params = None;
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let timeout = Some(Duration::from_secs(10));
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match client
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.initialize(params, initialize_notification_params, timeout)
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.await
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{
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Ok(_response) => (server_name, Ok(client)),
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Err(e) => (server_name, Err(e)),
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}
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}
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Err(e) => (server_name, Err(e.into())),
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}
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});
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}
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let mut clients: HashMap<String, std::sync::Arc<McpClient>> =
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HashMap::with_capacity(join_set.len());
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while let Some(res) = join_set.join_next().await {
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let (server_name, client_res) = res?; // JoinError propagation
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match client_res {
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Ok(client) => {
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clients.insert(server_name, std::sync::Arc::new(client));
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}
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Err(e) => {
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errors.insert(server_name, e);
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}
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}
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}
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let all_tools = list_all_tools(&clients).await?;
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let tools = qualify_tools(all_tools);
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Ok((Self { clients, tools }, errors))
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}
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/// Returns a single map that contains **all** tools. Each key is the
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/// fully-qualified name for the tool.
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pub fn list_all_tools(&self) -> HashMap<String, Tool> {
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self.tools
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.iter()
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.map(|(name, tool)| (name.clone(), tool.tool.clone()))
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.collect()
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}
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/// Invoke the tool indicated by the (server, tool) pair.
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pub async fn call_tool(
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&self,
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server: &str,
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tool: &str,
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arguments: Option<serde_json::Value>,
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timeout: Option<Duration>,
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) -> Result<mcp_types::CallToolResult> {
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let client = self
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.clients
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.get(server)
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.ok_or_else(|| anyhow!("unknown MCP server '{server}'"))?
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.clone();
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client
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.call_tool(tool.to_string(), arguments, timeout)
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.await
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.with_context(|| format!("tool call failed for `{server}/{tool}`"))
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}
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pub fn parse_tool_name(&self, tool_name: &str) -> Option<(String, String)> {
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self.tools
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.get(tool_name)
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.map(|tool| (tool.server_name.clone(), tool.tool_name.clone()))
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}
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}
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/// Query every server for its available tools and return a single map that
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/// contains **all** tools. Each key is the fully-qualified name for the tool.
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async fn list_all_tools(
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clients: &HashMap<String, std::sync::Arc<McpClient>>,
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) -> Result<Vec<ToolInfo>> {
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let mut join_set = JoinSet::new();
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// Spawn one task per server so we can query them concurrently. This
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// keeps the overall latency roughly at the slowest server instead of
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// the cumulative latency.
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for (server_name, client) in clients {
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let server_name_cloned = server_name.clone();
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let client_clone = client.clone();
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join_set.spawn(async move {
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let res = client_clone
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.list_tools(None, Some(LIST_TOOLS_TIMEOUT))
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.await;
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(server_name_cloned, res)
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});
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}
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let mut aggregated: Vec<ToolInfo> = Vec::with_capacity(join_set.len());
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while let Some(join_res) = join_set.join_next().await {
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let (server_name, list_result) = join_res?;
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let list_result = list_result?;
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for tool in list_result.tools {
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let tool_info = ToolInfo {
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server_name: server_name.clone(),
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tool_name: tool.name.clone(),
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tool,
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};
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aggregated.push(tool_info);
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}
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}
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info!(
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"aggregated {} tools from {} servers",
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aggregated.len(),
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clients.len()
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);
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Ok(aggregated)
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}
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fn is_valid_mcp_server_name(server_name: &str) -> bool {
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!server_name.is_empty()
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&& server_name
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.chars()
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.all(|c| c.is_ascii_alphanumeric() || c == '_' || c == '-')
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}
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#[cfg(test)]
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#[allow(clippy::unwrap_used)]
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mod tests {
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use super::*;
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use mcp_types::ToolInputSchema;
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fn create_test_tool(server_name: &str, tool_name: &str) -> ToolInfo {
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ToolInfo {
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server_name: server_name.to_string(),
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tool_name: tool_name.to_string(),
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tool: Tool {
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annotations: None,
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description: Some(format!("Test tool: {tool_name}")),
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input_schema: ToolInputSchema {
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properties: None,
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required: None,
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r#type: "object".to_string(),
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},
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name: tool_name.to_string(),
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output_schema: None,
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title: None,
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},
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}
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}
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#[test]
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fn test_qualify_tools_short_non_duplicated_names() {
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let tools = vec![
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create_test_tool("server1", "tool1"),
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create_test_tool("server1", "tool2"),
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];
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let qualified_tools = qualify_tools(tools);
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assert_eq!(qualified_tools.len(), 2);
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assert!(qualified_tools.contains_key("server1__tool1"));
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assert!(qualified_tools.contains_key("server1__tool2"));
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}
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#[test]
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fn test_qualify_tools_duplicated_names_skipped() {
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let tools = vec![
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create_test_tool("server1", "duplicate_tool"),
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create_test_tool("server1", "duplicate_tool"),
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];
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let qualified_tools = qualify_tools(tools);
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// Only the first tool should remain, the second is skipped
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assert_eq!(qualified_tools.len(), 1);
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assert!(qualified_tools.contains_key("server1__duplicate_tool"));
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}
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#[test]
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fn test_qualify_tools_long_names_same_server() {
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let server_name = "my_server";
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let tools = vec![
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create_test_tool(
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server_name,
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"extremely_lengthy_function_name_that_absolutely_surpasses_all_reasonable_limits",
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),
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create_test_tool(
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server_name,
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"yet_another_extremely_lengthy_function_name_that_absolutely_surpasses_all_reasonable_limits",
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),
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];
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let qualified_tools = qualify_tools(tools);
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assert_eq!(qualified_tools.len(), 2);
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let mut keys: Vec<_> = qualified_tools.keys().cloned().collect();
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keys.sort();
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assert_eq!(keys[0].len(), 64);
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assert_eq!(
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keys[0],
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"my_server__extremely_lena02e507efc5a9de88637e436690364fd4219e4ef"
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);
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assert_eq!(keys[1].len(), 64);
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assert_eq!(
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keys[1],
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"my_server__yet_another_e1c3987bd9c50b826cbe1687966f79f0c602d19ca"
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);
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}
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}
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