diff --git a/dotnet/README.md b/dotnet/README.md
index 796ef22549..83398aff2c 100644
--- a/dotnet/README.md
+++ b/dotnet/README.md
@@ -64,6 +64,12 @@ await session.SendAsync(new MessageOptions { Prompt = "What is 2+2?" });
 await done.Task;
 ```
 
+When targeting MCP tools configured through `McpServers`, remember the runtime
+tool name is `<server-key>-<tool-name>`. For `AvailableTools` and
+`ExcludedTools`, prefer the source-qualified form
+`mcp:<server-key>-<tool-name>`. For `CustomAgents[].Tools` and
+`DefaultAgent.ExcludedTools`, use `<server-key>-<tool-name>` directly.
+
 ## API Reference
 
 ### CopilotClient
diff --git a/go/README.md b/go/README.md
index 5787e5a53e..f3f98572cc 100644
--- a/go/README.md
+++ b/go/README.md
@@ -89,6 +89,12 @@ func main() {
 }
 ```
 
+When targeting MCP tools configured through `MCPServers`, remember the runtime
+tool name is `<server-key>-<tool-name>`. For `AvailableTools` and
+`ExcludedTools`, prefer the source-qualified form
+`mcp:<server-key>-<tool-name>`. For `CustomAgents[].Tools` and
+`DefaultAgent.ExcludedTools`, use `<server-key>-<tool-name>` directly.
+
 ## Distributing your application with an embedded GitHub Copilot CLI
 
 The SDK supports bundling, using Go's `embed` package, the Copilot CLI binary within your application's distribution.
diff --git a/java/README.md b/java/README.md
index 42e438e527..13e56123b8 100644
--- a/java/README.md
+++ b/java/README.md
@@ -120,6 +120,13 @@ public class CopilotSDK {
 }
 ```
 
+When targeting MCP tools configured through `setMcpServers(...)`, remember the
+runtime tool name is `<server-key>-<tool-name>`. For `setAvailableTools(...)`
+and `setExcludedTools(...)`, prefer the source-qualified filter form
+`mcp:<server-key>-<tool-name>`. For `CustomAgentConfig.setTools(...)` and
+`DefaultAgentConfig.setExcludedTools(...)`, use `<server-key>-<tool-name>`
+directly.
+
 ## Try it with JBang
 
 You can run the SDK without setting up a full Java project, by using [JBang](https://www.jbang.dev/).
diff --git a/nodejs/README.md b/nodejs/README.md
index e9d83c6df9..7c050fdf8d 100644
--- a/nodejs/README.md
+++ b/nodejs/README.md
@@ -71,6 +71,12 @@ await using session = await client.createSession({
 // session is automatically disconnected when leaving scope
 ```
 
+When targeting MCP tools configured through `mcpServers`, remember the runtime
+tool name is `<server-key>-<tool-name>`. For `availableTools` and
+`excludedTools`, prefer `new ToolSet().addMcp("<server-key>-<tool-name>")` or
+the raw `mcp:<server-key>-<tool-name>` form. For `customAgents[].tools` and
+`defaultAgent.excludedTools`, use `<server-key>-<tool-name>` directly.
+
 ## API Reference
 
 ### CopilotClient
diff --git a/python/README.md b/python/README.md
index 86f568bd7a..669b8798d5 100644
--- a/python/README.md
+++ b/python/README.md
@@ -220,6 +220,7 @@ These are passed as keyword arguments to `create_session()`:
 - `on_permission_request` (callable): Optional handler called before each tool execution to approve or deny it. When omitted, permission requests are emitted as events and left pending for manual resolution. Use `PermissionHandler.approve_all` to allow everything, or provide a custom function for fine-grained control. See [Permission Handling](#permission-handling) section.
 - `on_user_input_request` (callable): Handler for user input requests from the agent (enables ask_user tool). See [User Input Requests](#user-input-requests) section.
 - `hooks` (SessionHooks): Hook handlers for session lifecycle events. See [Session Hooks](#session-hooks) section.
+- `available_tools` / `excluded_tools` / `default_agent.excluded_tools` / custom-agent `tools`: MCP tools registered from `mcp_servers` are exposed to the runtime as `<server-key>-<tool-name>`. For `available_tools` and `excluded_tools`, prefer `ToolSet().add_mcp("<server-key>-<tool-name>")` or the raw `mcp:<server-key>-<tool-name>` form. For custom-agent `tools` and `default_agent.excluded_tools`, use `<server-key>-<tool-name>` directly.
 
 **Session Lifecycle Methods:**
 
diff --git a/rust/README.md b/rust/README.md
index 6d92224088..985d35b156 100644
--- a/rust/README.md
+++ b/rust/README.md
@@ -31,6 +31,12 @@ client.stop().await.ok();
 # }
 ```
 
+When targeting MCP tools configured through `mcp_servers`, remember the runtime
+tool name is `<server-key>-<tool-name>`. For `available_tools` and
+`excluded_tools`, prefer `ToolSet::new().add_mcp("<server-key>-<tool-name>")`
+or the raw `mcp:<server-key>-<tool-name>` form. For `custom_agents[].tools`
+and `default_agent.excluded_tools`, use `<server-key>-<tool-name>` directly.
+
 ## Architecture
 
 ```text