[MCP] Add support for resources (#5239)

This PR adds support for [MCP
resources](https://modelcontextprotocol.io/specification/2025-06-18/server/resources)
by adding three new tools for the model:
1. `list_resources`
2. `list_resource_templates`
3. `read_resource`

These 3 tools correspond to the [three primary MCP resource protocol
messages](https://modelcontextprotocol.io/specification/2025-06-18/server/resources#protocol-messages).

Example of listing and reading a GitHub resource tempalte
<img width="2984" height="804" alt="CleanShot 2025-10-15 at 17 31 10"
src="https://github.com/user-attachments/assets/89b7f215-2e2a-41c5-90dd-b932ac84a585"
/>

`/mcp` with Figma configured
<img width="2984" height="442" alt="CleanShot 2025-10-15 at 18 29 35"
src="https://github.com/user-attachments/assets/a7578080-2ed2-4c59-b9b4-d8461f90d8ee"
/>

Fixes #4956

codex-rs/tui/src/chatwidget.rs

@@ -2071,6 +2071,8 @@ impl ChatWidget {
         self.add_to_history(history_cell::new_mcp_tools_output(
             &self.config,
             ev.tools,
+            ev.resources,
+            ev.resource_templates,
             &ev.auth_statuses,
         ));
     }

codex-rs/tui/src/history_cell.rs

@@ -35,7 +35,9 @@ use codex_protocol::plan_tool::UpdatePlanArgs;
 use image::DynamicImage;
 use image::ImageReader;
 use mcp_types::EmbeddedResourceResource;
+use mcp_types::Resource;
 use mcp_types::ResourceLink;
+use mcp_types::ResourceTemplate;
 use ratatui::prelude::*;
 use ratatui::style::Modifier;
 use ratatui::style::Style;
@@ -976,6 +978,8 @@ pub(crate) fn empty_mcp_output() -> PlainHistoryCell {
 pub(crate) fn new_mcp_tools_output(
     config: &Config,
     tools: HashMap<String, mcp_types::Tool>,
+    resources: HashMap<String, Vec<Resource>>,
+    resource_templates: HashMap<String, Vec<ResourceTemplate>>,
     auth_statuses: &HashMap<String, McpAuthStatus>,
 ) -> PlainHistoryCell {
     let mut lines: Vec<Line<'static>> = vec![
@@ -1073,12 +1077,64 @@ pub(crate) fn new_mcp_tools_output(
         }
 
         if !cfg.enabled {
-            lines.push(vec!["    • Tools: ".into(), "(disabled)".red()].into());
-        } else if names.is_empty() {
+            let disabled = "(disabled)".red();
+            lines.push(vec!["    • Tools: ".into(), disabled.clone()].into());
+            lines.push(vec!["    • Resources: ".into(), disabled.clone()].into());
+            lines.push(vec!["    • Resource templates: ".into(), disabled].into());
+            lines.push(Line::from(""));
+            continue;
+        }
+
+        if names.is_empty() {
             lines.push("    • Tools: (none)".into());
         } else {
             lines.push(vec!["    • Tools: ".into(), names.join(", ").into()].into());
         }
+
+        let server_resources: Vec<Resource> =
+            resources.get(server.as_str()).cloned().unwrap_or_default();
+        if server_resources.is_empty() {
+            lines.push("    • Resources: (none)".into());
+        } else {
+            let mut spans: Vec<Span<'static>> = vec!["    • Resources: ".into()];
+
+            for (idx, resource) in server_resources.iter().enumerate() {
+                if idx > 0 {
+                    spans.push(", ".into());
+                }
+
+                let label = resource.title.as_ref().unwrap_or(&resource.name);
+                spans.push(label.clone().into());
+                spans.push(" ".into());
+                spans.push(format!("({})", resource.uri).dim());
+            }
+
+            lines.push(spans.into());
+        }
+
+        let server_templates: Vec<ResourceTemplate> = resource_templates
+            .get(server.as_str())
+            .cloned()
+            .unwrap_or_default();
+        if server_templates.is_empty() {
+            lines.push("    • Resource templates: (none)".into());
+        } else {
+            let mut spans: Vec<Span<'static>> = vec!["    • Resource templates: ".into()];
+
+            for (idx, template) in server_templates.iter().enumerate() {
+                if idx > 0 {
+                    spans.push(", ".into());
+                }
+
+                let label = template.title.as_ref().unwrap_or(&template.name);
+                spans.push(label.clone().into());
+                spans.push(" ".into());
+                spans.push(format!("({})", template.uri_template).dim());
+            }
+
+            lines.push(spans.into());
+        }
+
         lines.push(Line::from(""));
     }