feat: Support claude-style hidden workspace MCP configuration files via .mcp.json

config.example.yaml

@@ -138,8 +138,10 @@ enabled_mcp_servers: null        # Which MCP servers to enable by default.
                                  #   enabled_mcp_servers: github,slack,ddg-search
 no_workspace_mcp: false          # Disable loading workspace-local MCP servers from .coyote/mcp.json (default: false).
                                  # When false (the default), Coyote merges .coyote/mcp.json from the current directory
-                                 # into the global MCP registry at startup. Workspace entries shadow global ones on
-                                 # name collision. Set to true (or pass --no-workspace-mcp) to skip this entirely.
+                                 # into the global MCP registry at startup. If mcp.json is absent, Coyote falls back
+                                 # to .coyote/.mcp.json (leading dot) for compatibility with Claude-style
+                                 # configurations. Workspace entries shadow global ones on name collision.
+                                 # Set to true (or pass --no-workspace-mcp) to skip this entirely.
 
 # ---- Skills ----
 # Skills are modular knowledge or capability packs the LLM can load and unload mid-conversation.

src/cli/mod.rs

@@ -71,7 +71,7 @@ pub struct Cli {
     /// Display the message without sending it
     #[arg(long)]
     pub dry_run: bool,
-    /// Disable loading workspace MCP servers from .coyote/mcp.json
+    /// Disable loading workspace MCP servers from .coyote/mcp.json (or .coyote/.mcp.json)
     #[arg(long)]
     pub no_workspace_mcp: bool,
     /// Disable memory for this invocation

src/config/mod.rs

@@ -140,6 +140,7 @@ const GLOBAL_TOOLS_DIR_NAME: &str = "tools";
 const GLOBAL_TOOLS_UTILS_DIR_NAME: &str = "utils";
 const BASH_PROMPT_UTILS_FILE_NAME: &str = "prompt-utils.sh";
 const MCP_FILE_NAME: &str = "mcp.json";
+const HIDDEN_MCP_FILE_NAME: &str = ".mcp.json";
 const MEMORY_DIR_NAME: &str = "memory";
 const MEMORY_INDEX_FILE_NAME: &str = "MEMORY.md";
 const WORKSPACE_MEMORY_FILE_NAME: &str = "COYOTE.md";

src/config/paths.rs

@@ -2,10 +2,10 @@ use super::role::Role;
 use super::{
     AGENT_GRAPH_FILE_NAME, AGENTS_DIR_NAME, BASH_PROMPT_UTILS_FILE_NAME, CONFIG_FILE_NAME,
     ENV_FILE_NAME, FUNCTIONS_BIN_DIR_NAME, FUNCTIONS_DIR_NAME, GLOBAL_TOOLS_DIR_NAME,
-    GLOBAL_TOOLS_UTILS_DIR_NAME, MACROS_DIR_NAME, MCP_FILE_NAME, MEMORY_DIR_NAME,
-    MEMORY_INDEX_FILE_NAME, ModelsOverride, RAGS_DIR_NAME, ROLES_DIR_NAME, SBX_KIT_DIR_NAME,
-    SBX_KIT_HASH_FILE, SBX_MIXIN_FILE_NAME, SBX_MIXIN_KITS_DIR_NAME, SBX_VAULT_MIXINS_DIR_NAME,
-    SKILLS_DIR_NAME, WORKSPACE_COYOTE_DIR_NAME,
+    GLOBAL_TOOLS_UTILS_DIR_NAME, HIDDEN_MCP_FILE_NAME, MACROS_DIR_NAME, MCP_FILE_NAME,
+    MEMORY_DIR_NAME, MEMORY_INDEX_FILE_NAME, ModelsOverride, RAGS_DIR_NAME, ROLES_DIR_NAME,
+    SBX_KIT_DIR_NAME, SBX_KIT_HASH_FILE, SBX_MIXIN_FILE_NAME, SBX_MIXIN_KITS_DIR_NAME,
+    SBX_VAULT_MIXINS_DIR_NAME, SKILLS_DIR_NAME, WORKSPACE_COYOTE_DIR_NAME,
 };
 use crate::client::ProviderModels;
 use crate::config::REPL_HISTORY_DIR_NAME;
@@ -212,10 +212,12 @@ pub fn workspace_skill_file(name: &str) -> PathBuf {
     workspace_skills_dir().join(name).join("SKILL.md")
 }
 
-pub fn workspace_mcp_config_file() -> PathBuf {
-    workspace_config_dir()
-        .join(WORKSPACE_COYOTE_DIR_NAME)
-        .join(MCP_FILE_NAME)
+pub fn workspace_mcp_config_file() -> Option<PathBuf> {
+    let dir = workspace_config_dir();
+    [MCP_FILE_NAME, HIDDEN_MCP_FILE_NAME]
+        .into_iter()
+        .map(|name| dir.join(name))
+        .find(|candidate| candidate.is_file())
 }
 
 pub fn validate_skill_name(name: &str) -> Result<()> {
@@ -689,6 +691,69 @@ mod tests {
         }
     }
 
+    mod workspace_mcp_resolution {
+        use super::*;
+        use serial_test::serial;
+
+        fn with_workspace_dir<F: FnOnce(&Path)>(f: F) {
+            let unique = time::SystemTime::now()
+                .duration_since(time::UNIX_EPOCH)
+                .unwrap()
+                .as_nanos();
+            let root = env::temp_dir().join(format!("coyote-workspace-mcp-test-{unique}"));
+            fs::create_dir_all(&root).unwrap();
+            let env_name = get_env_name("workspace_config_dir");
+            let prev = env::var_os(&env_name);
+            unsafe {
+                env::set_var(&env_name, &root);
+            }
+            f(&root);
+            unsafe {
+                match prev {
+                    Some(v) => env::set_var(&env_name, v),
+                    None => env::remove_var(&env_name),
+                }
+            }
+            let _ = fs::remove_dir_all(&root);
+        }
+
+        #[test]
+        #[serial]
+        fn returns_none_when_no_config_exists() {
+            with_workspace_dir(|_| {
+                assert_eq!(workspace_mcp_config_file(), None);
+            });
+        }
+
+        #[test]
+        #[serial]
+        fn finds_mcp_json() {
+            with_workspace_dir(|root| {
+                fs::write(root.join("mcp.json"), "{}").unwrap();
+                assert_eq!(workspace_mcp_config_file(), Some(root.join("mcp.json")));
+            });
+        }
+
+        #[test]
+        #[serial]
+        fn falls_back_to_claude_style_hidden_mcp_json() {
+            with_workspace_dir(|root| {
+                fs::write(root.join(".mcp.json"), "{}").unwrap();
+                assert_eq!(workspace_mcp_config_file(), Some(root.join(".mcp.json")));
+            });
+        }
+
+        #[test]
+        #[serial]
+        fn prefers_mcp_json_when_both_exist() {
+            with_workspace_dir(|root| {
+                fs::write(root.join("mcp.json"), "{}").unwrap();
+                fs::write(root.join(".mcp.json"), "{}").unwrap();
+                assert_eq!(workspace_mcp_config_file(), Some(root.join("mcp.json")));
+            });
+        }
+    }
+
     #[test]
     fn sandbox_kit_override_reflects_env_var_state() {
         let env_name = get_env_name("sandbox_kit");

src/mcp/mod.rs

@@ -215,49 +215,48 @@ impl McpRegistry {
         }
 
         let mut merged = mcp_servers_config;
-        if !app_config.no_workspace_mcp {
-            let ws_path = paths::workspace_mcp_config_file();
-            if ws_path.try_exists().unwrap_or(false) {
-                match tokio::fs::read_to_string(&ws_path).await {
-                    Ok(ws_content) if !ws_content.trim().is_empty() => {
-                        match interpolate_secrets(&ws_content, vault) {
-                            Ok((parsed, missing)) if missing.is_empty() => {
-                                match serde_json::from_str::<McpServersConfig>(&parsed) {
-                                    Ok(ws_config) => {
-                                        let mut loaded = Vec::new();
-                                        for (name, spec) in ws_config.mcp_servers {
-                                            match spec.validate(&name) {
-                                                Ok(_) => {
-                                                    loaded.push(name.clone());
-                                                    merged.mcp_servers.insert(name, spec);
-                                                }
-                                                Err(e) => warn!(
-                                                    "Invalid workspace MCP server '{name}': {e}. Skipping."
-                                                ),
+        if !app_config.no_workspace_mcp
+            && let Some(ws_path) = paths::workspace_mcp_config_file()
+        {
+            match tokio::fs::read_to_string(&ws_path).await {
+                Ok(ws_content) if !ws_content.trim().is_empty() => {
+                    match interpolate_secrets(&ws_content, vault) {
+                        Ok((parsed, missing)) if missing.is_empty() => {
+                            match serde_json::from_str::<McpServersConfig>(&parsed) {
+                                Ok(ws_config) => {
+                                    let mut loaded = Vec::new();
+                                    for (name, spec) in ws_config.mcp_servers {
+                                        match spec.validate(&name) {
+                                            Ok(_) => {
+                                                loaded.push(name.clone());
+                                                merged.mcp_servers.insert(name, spec);
                                             }
-                                        }
-                                        if !loaded.is_empty() {
-                                            eprintln!(
-                                                "Loading workspace MCP servers: {}",
-                                                loaded.join(", ")
-                                            );
+                                            Err(e) => warn!(
+                                                "Invalid workspace MCP server '{name}': {e}. Skipping."
+                                            ),
                                         }
                                     }
-                                    Err(e) => warn!(
-                                        "Failed to parse workspace MCP config: {e}. Skipping."
-                                    ),
+                                    if !loaded.is_empty() {
+                                        eprintln!(
+                                            "Loading workspace MCP servers: {}",
+                                            loaded.join(", ")
+                                        );
+                                    }
+                                }
+                                Err(e) => {
+                                    warn!("Failed to parse workspace MCP config: {e}. Skipping.")
                                 }
                             }
-                            Ok((_, missing)) => warn!(
-                                "Workspace MCP config references missing vault secrets: {missing:?}. Skipping."
-                            ),
-                            Err(e) => {
-                                warn!("Failed to process workspace MCP config: {e}. Skipping.")
-                            }
+                        }
+                        Ok((_, missing)) => warn!(
+                            "Workspace MCP config references missing vault secrets: {missing:?}. Skipping."
+                        ),
+                        Err(e) => {
+                            warn!("Failed to process workspace MCP config: {e}. Skipping.")
                         }
                     }
-                    _ => {}
                 }
+                _ => {}
             }
         }
         registry.config = Some(merged);