codex-tools: extract discoverable tool models (#16254)

## Why

`#16193` moved the pure `tool_search` and `tool_suggest` spec builders
into `codex-tools`, but `codex-core` still owned the shared
discoverable-tool model that those builders and the `tool_suggest`
runtime both depend on. This change continues the migration by moving
that reusable model boundary out of `codex-core` as well, so the
discovery/suggestion stack uses one shared set of types and
`core/src/tools` no longer needs its own `discoverable.rs` module.

## What changed

- Moved `DiscoverableTool`, `DiscoverablePluginInfo`, and
`filter_tool_suggest_discoverable_tools_for_client()` into
`codex-rs/tools/src/tool_discovery.rs` alongside the extracted
discovery/suggestion spec builders.
- Added `codex-app-server-protocol` as a `codex-tools` dependency so the
shared discoverable-tool model can own the connector-side `AppInfo`
variant directly.
- Updated `core/src/tools/handlers/tool_suggest.rs`,
`core/src/tools/spec.rs`, `core/src/tools/router.rs`,
`core/src/connectors.rs`, and `core/src/codex.rs` to consume the shared
`codex-tools` model instead of the old core-local declarations.
- Changed `core/src/plugins/discoverable.rs` to return
`DiscoverablePluginInfo` directly, moved the pure client-filter coverage
into `tool_discovery_tests.rs`, and deleted the old
`core/src/tools/discoverable.rs` module.
- Updated `codex-rs/tools/README.md` so the crate boundary documents
that `codex-tools` now owns the discoverable-tool models in addition to
the discovery/suggestion spec builders.

## Test plan

- `cargo test -p codex-tools`
- `CARGO_TARGET_DIR=/tmp/codex-core-discoverable-model cargo test -p
codex-core --lib tools::handlers::tool_suggest::`
- `CARGO_TARGET_DIR=/tmp/codex-core-discoverable-model cargo test -p
codex-core --lib tools::spec::`
- `CARGO_TARGET_DIR=/tmp/codex-core-discoverable-model cargo test -p
codex-core --lib plugins::discoverable::`
- `just bazel-lock-check`
- `just argument-comment-lint`

## References

- #16193
- #16154
- #15923
- #15928
- #15944
- #15953
- #16031
- #16047
- #16129
- #16132
- #16138
- #16141

codex-rs/core/src/tools/discoverable.rs

@@ -1,94 +0,0 @@
-use crate::plugins::PluginCapabilitySummary;
-use codex_app_server_protocol::AppInfo;
-use codex_tools::DiscoverableToolType;
-
-const TUI_CLIENT_NAME: &str = "codex-tui";
-
-#[derive(Clone, Debug, PartialEq)]
-pub(crate) enum DiscoverableTool {
-    Connector(Box<AppInfo>),
-    Plugin(Box<DiscoverablePluginInfo>),
-}
-
-impl DiscoverableTool {
-    pub(crate) fn tool_type(&self) -> DiscoverableToolType {
-        match self {
-            Self::Connector(_) => DiscoverableToolType::Connector,
-            Self::Plugin(_) => DiscoverableToolType::Plugin,
-        }
-    }
-
-    pub(crate) fn id(&self) -> &str {
-        match self {
-            Self::Connector(connector) => connector.id.as_str(),
-            Self::Plugin(plugin) => plugin.id.as_str(),
-        }
-    }
-
-    pub(crate) fn name(&self) -> &str {
-        match self {
-            Self::Connector(connector) => connector.name.as_str(),
-            Self::Plugin(plugin) => plugin.name.as_str(),
-        }
-    }
-
-    pub(crate) fn install_url(&self) -> Option<&str> {
-        match self {
-            Self::Connector(connector) => connector.install_url.as_deref(),
-            Self::Plugin(_) => None,
-        }
-    }
-}
-
-impl From<AppInfo> for DiscoverableTool {
-    fn from(value: AppInfo) -> Self {
-        Self::Connector(Box::new(value))
-    }
-}
-
-impl From<DiscoverablePluginInfo> for DiscoverableTool {
-    fn from(value: DiscoverablePluginInfo) -> Self {
-        Self::Plugin(Box::new(value))
-    }
-}
-
-pub(crate) fn filter_tool_suggest_discoverable_tools_for_client(
-    discoverable_tools: Vec<DiscoverableTool>,
-    app_server_client_name: Option<&str>,
-) -> Vec<DiscoverableTool> {
-    if app_server_client_name != Some(TUI_CLIENT_NAME) {
-        return discoverable_tools;
-    }
-
-    discoverable_tools
-        .into_iter()
-        .filter(|tool| !matches!(tool, DiscoverableTool::Plugin(_)))
-        .collect()
-}
-
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub(crate) struct DiscoverablePluginInfo {
-    pub(crate) id: String,
-    pub(crate) name: String,
-    pub(crate) description: Option<String>,
-    pub(crate) has_skills: bool,
-    pub(crate) mcp_server_names: Vec<String>,
-    pub(crate) app_connector_ids: Vec<String>,
-}
-
-impl From<PluginCapabilitySummary> for DiscoverablePluginInfo {
-    fn from(value: PluginCapabilitySummary) -> Self {
-        Self {
-            id: value.config_name,
-            name: value.display_name,
-            description: value.description,
-            has_skills: value.has_skills,
-            mcp_server_names: value.mcp_server_names,
-            app_connector_ids: value
-                .app_connector_ids
-                .into_iter()
-                .map(|connector_id| connector_id.0)
-                .collect(),
-        }
-    }
-}

codex-rs/core/src/tools/handlers/tool_suggest.rs

@@ -8,8 +8,10 @@ use codex_app_server_protocol::McpElicitationSchema;
 use codex_app_server_protocol::McpServerElicitationRequest;
 use codex_app_server_protocol::McpServerElicitationRequestParams;
 use codex_rmcp_client::ElicitationAction;
+use codex_tools::DiscoverableTool;
 use codex_tools::DiscoverableToolAction;
 use codex_tools::DiscoverableToolType;
+use codex_tools::filter_tool_suggest_discoverable_tools_for_client;
 use rmcp::model::RequestId;
 use serde::Deserialize;
 use serde::Serialize;
@@ -22,8 +24,6 @@ use crate::mcp::CODEX_APPS_MCP_SERVER_NAME;
 use crate::tools::context::FunctionToolOutput;
 use crate::tools::context::ToolInvocation;
 use crate::tools::context::ToolPayload;
-use crate::tools::discoverable::DiscoverableTool;
-use crate::tools::discoverable::filter_tool_suggest_discoverable_tools_for_client;
 use crate::tools::handlers::parse_arguments;
 use crate::tools::registry::ToolHandler;
 use crate::tools::registry::ToolKind;

codex-rs/core/src/tools/handlers/tool_suggest_tests.rs

@@ -5,9 +5,9 @@ use crate::plugins::test_support::load_plugins_config;
 use crate::plugins::test_support::write_curated_plugin_sha;
 use crate::plugins::test_support::write_openai_curated_marketplace;
 use crate::plugins::test_support::write_plugins_feature_config;
-use crate::tools::discoverable::DiscoverablePluginInfo;
-use crate::tools::discoverable::filter_tool_suggest_discoverable_tools_for_client;
 use codex_app_server_protocol::AppInfo;
+use codex_tools::DiscoverablePluginInfo;
+use codex_tools::DiscoverableTool;
 use codex_tools::DiscoverableToolAction;
 use codex_tools::DiscoverableToolType;
 use codex_utils_absolute_path::AbsolutePathBuf;
@@ -161,54 +161,6 @@ fn build_tool_suggestion_meta_uses_expected_shape() {
     );
 }
 
-#[test]
-fn filter_tool_suggest_discoverable_tools_for_codex_tui_omits_plugins() {
-    let discoverable_tools = vec![
-        DiscoverableTool::Connector(Box::new(AppInfo {
-            id: "connector_google_calendar".to_string(),
-            name: "Google Calendar".to_string(),
-            description: Some("Plan events and schedules.".to_string()),
-            logo_url: None,
-            logo_url_dark: None,
-            distribution_channel: None,
-            branding: None,
-            app_metadata: None,
-            labels: None,
-            install_url: Some("https://example.test/google-calendar".to_string()),
-            is_accessible: false,
-            is_enabled: true,
-            plugin_display_names: Vec::new(),
-        })),
-        DiscoverableTool::Plugin(Box::new(DiscoverablePluginInfo {
-            id: "slack@openai-curated".to_string(),
-            name: "Slack".to_string(),
-            description: Some("Search Slack messages".to_string()),
-            has_skills: true,
-            mcp_server_names: vec!["slack".to_string()],
-            app_connector_ids: vec!["connector_slack".to_string()],
-        })),
-    ];
-
-    assert_eq!(
-        filter_tool_suggest_discoverable_tools_for_client(discoverable_tools, Some("codex-tui"),),
-        vec![DiscoverableTool::Connector(Box::new(AppInfo {
-            id: "connector_google_calendar".to_string(),
-            name: "Google Calendar".to_string(),
-            description: Some("Plan events and schedules.".to_string()),
-            logo_url: None,
-            logo_url_dark: None,
-            distribution_channel: None,
-            branding: None,
-            app_metadata: None,
-            labels: None,
-            install_url: Some("https://example.test/google-calendar".to_string()),
-            is_accessible: false,
-            is_enabled: true,
-            plugin_display_names: Vec::new(),
-        }))]
-    );
-}
-
 #[test]
 fn verified_connector_suggestion_completed_requires_accessible_connector() {
     let accessible_connectors = vec![AppInfo {

codex-rs/core/src/tools/mod.rs

@@ -1,6 +1,5 @@
 pub mod code_mode;
 pub mod context;
-pub(crate) mod discoverable;
 pub mod events;
 pub(crate) mod handlers;
 pub mod js_repl;

codex-rs/core/src/tools/router.rs

@@ -7,7 +7,6 @@ use crate::sandboxing::SandboxPermissions;
 use crate::tools::context::SharedTurnDiffTracker;
 use crate::tools::context::ToolInvocation;
 use crate::tools::context::ToolPayload;
-use crate::tools::discoverable::DiscoverableTool;
 use crate::tools::registry::AnyToolResult;
 use crate::tools::registry::ToolRegistry;
 use crate::tools::spec::ToolsConfig;
@@ -18,6 +17,7 @@ use codex_protocol::models::ResponseItem;
 use codex_protocol::models::SearchToolCallParams;
 use codex_protocol::models::ShellToolCallParams;
 use codex_tools::ConfiguredToolSpec;
+use codex_tools::DiscoverableTool;
 use rmcp::model::Tool;
 use std::collections::HashMap;
 use std::sync::Arc;

codex-rs/core/src/tools/spec.rs

@@ -7,7 +7,6 @@ use crate::shell::Shell;
 use crate::shell::ShellType;
 use crate::tools::code_mode::PUBLIC_TOOL_NAME;
 use crate::tools::code_mode::WAIT_TOOL_NAME;
-use crate::tools::discoverable::DiscoverableTool;
 use crate::tools::handlers::PLAN_TOOL;
 use crate::tools::handlers::TOOL_SEARCH_DEFAULT_LIMIT;
 use crate::tools::handlers::TOOL_SEARCH_TOOL_NAME;
@@ -38,6 +37,7 @@ use codex_protocol::protocol::SandboxPolicy;
 use codex_protocol::protocol::SessionSource;
 use codex_protocol::protocol::SubAgentSource;
 use codex_tools::CommandToolOptions;
+use codex_tools::DiscoverableTool;
 use codex_tools::DiscoverableToolType;
 use codex_tools::ShellToolOptions;
 use codex_tools::SpawnAgentToolOptions;

codex-rs/core/src/tools/spec_tests.rs

@@ -4,7 +4,6 @@ use crate::models_manager::model_info::with_config_overrides;
 use crate::shell::Shell;
 use crate::shell::ShellType;
 use crate::tools::ToolRouter;
-use crate::tools::discoverable::DiscoverablePluginInfo;
 use crate::tools::router::ToolRouterParams;
 use codex_app_server_protocol::AppInfo;
 use codex_protocol::models::VIEW_IMAGE_TOOL_NAME;
@@ -14,6 +13,8 @@ use codex_protocol::openai_models::ModelsResponse;
 use codex_tools::AdditionalProperties;
 use codex_tools::CommandToolOptions;
 use codex_tools::ConfiguredToolSpec;
+use codex_tools::DiscoverablePluginInfo;
+use codex_tools::DiscoverableTool;
 use codex_tools::FreeformTool;
 use codex_tools::ResponsesApiTool;
 use codex_tools::ResponsesApiWebSearchFilters;