# Test an MCP Server’s Tools with the Inspector > For the complete documentation index, see [llms.txt](https://docs.redpanda.com/llms.txt). Component-specific: [agentic-data-plane-full.txt](https://docs.redpanda.com/agentic-data-plane-full.txt) --- title: Test an MCP Server’s Tools with the Inspector latest-operator-version: v26.1.5 latest-console-tag: v3.7.4 latest-connect-version: 4.96.1 latest-redpanda-tag: v26.1.10 docname: test-tools page-component-name: agentic-data-plane page-version: master page-component-version: master page-component-title: Agentic Data Plane page-relative-src-path: test-tools.adoc page-edit-url: https://github.com/redpanda-data/adp-docs/edit/main/modules/connect/pages/test-tools.adoc description: Use the Inspector tab to call tools, inspect resources and prompts, and verify your MCP server works without standing up an agent. page-topic-type: how-to personas: agent_builder learning-objective-1: Run an MCP tool from the Inspector and read its response learning-objective-2: Inspect resources, prompts, and call history learning-objective-3: Diagnose common errors (missing authentication, scope upgrade required, transport mismatch) before pointing an agent at the server page-git-created-date: "2026-05-28" page-git-modified-date: "2026-06-10" --- Verify that your MCP server’s [tools](https://docs.redpanda.com/agentic-data-plane/reference/glossary/#tool), [resources](https://docs.redpanda.com/agentic-data-plane/reference/glossary/#resource), and [prompts](https://docs.redpanda.com/agentic-data-plane/reference/glossary/#prompt) work correctly before agents depend on them. The Inspector runs on the same JSON-RPC connection agents use, so a passing test means fewer failed tool calls in production. Use the Inspector after creating a server or whenever you change a tool’s schema. After completing this guide, you will be able to: - Run an MCP tool from the Inspector and read its response - Inspect resources, prompts, and call history - Diagnose common errors (missing authentication, scope upgrade required, transport mismatch) before pointing an agent at the server ## [](#when-to-use-the-inspector)When to use the Inspector - After creating or registering a server, to confirm tool discovery completed and tools run correctly. - While iterating on a self-managed server, to test schema changes against a live connection. - When debugging an agent failure, to isolate whether the issue is in the agent or in the MCP server itself. ## [](#open-the-inspector)Open the Inspector 1. Open **MCP Servers** in the sidebar and click into your server. 2. Switch to the **Inspector** tab. The Inspector has four panels: **Tools**, **Resources**, **Prompts**, and **Session**. ## [](#tools-panel)Tools panel The Tools panel lists every tool the server returned from `tools/list`. 1. Select a tool from the list. The right-hand pane renders a form from the tool’s input JSON schema. 2. Fill in the form fields. 3. Click **Run**. The response appears below the form. If the tool returns an error, the response pane shows the structured error detail. See [Common errors](#errors) for what each common error means. ### [](#code-mode-tools)Code-mode tools If the server has **Code mode** enabled, the Tools panel also lists `{name}_search` and `{name}_execute` alongside the server’s regular tools. These are the helpers an agent uses to discover and orchestrate tools through generated Python or JavaScript. Test them like any other tool. ## [](#resources-panel)Resources panel The Resources panel lists any resources the server exposes through `resources/list`. Many MCP servers don’t expose resources at all: if the panel is empty, that’s fine. If your server does expose resources: 1. Click a resource to load its content into the right-hand pane. 2. The Inspector renders text, JSON, and binary types differently; binary types show a download link. ## [](#prompts-panel)Prompts panel The Prompts panel lists any prompt templates the server exposes through `prompts/list`. Prompt templates are parameterized prompts an agent can invoke by name. As with resources, many servers don’t expose prompts. If your server does expose prompts: 1. Click a prompt to render its template. 2. Fill in any required parameters in the rendered form. 3. Click **Run** to see the rendered prompt content. ## [](#session-panel)Session panel The Session panel keeps a running history of every call you’ve made through the Inspector: request, response, latency. Use it to: - Replay a previous call by clicking it in the history list. - Diff two responses side-by-side (useful when iterating on a tool’s logic). - Copy a request as JSON-RPC for use outside the Inspector. ## [](#errors)Common errors | Error | Meaning and fix | | --- | --- | | OAuthConnectionRequired | User-delegated auth has no stored token for the calling user. Redpanda includes an authorize_url in the error detail; complete the consent flow per User-delegated OAuth. | | OAuthTokenExpired | Stored token is expired and refresh failed. Re-consent through Connections. | | scope_upgrade_required | The user’s connection lacks one of the server’s required_scopes. Re-consent with the higher scope. | | Transport / connection error | The Inspector can’t reach the upstream. For self-managed servers, check the Connection tab on the detail page; verify the URL and transport choice. | | Tool input validation error | The form’s input doesn’t match the tool’s schema. The error message includes the offending field. Update and re-run. | ## [](#test-from-the-cli)Test from the CLI Use [`rpk ai`](https://docs.redpanda.com/agentic-data-plane/reference/rpk/rpk-ai/rpk-ai/) for the same tool calls outside the UI, when scripting smoke tests or running checks from CI. ```bash # List every tool exposed by a server rpk ai mcp tools list # Call a tool with a JSON arg blob rpk ai mcp tools call --input '{"arg1":"value"}' # Get server detail; includes the tool list by default. Add --no-tools # to skip discovery (faster when you only want metadata). rpk ai mcp get ``` The command resolves the gateway URL from your active rpk cloud profile and reads the cached `rpk cloud login` token. See [Connect your app to AI Gateway](https://docs.redpanda.com/agentic-data-plane/gateway/connect-agent/) for installation and profile setup. ## [](#next-steps)Next steps - [Code Mode](https://docs.redpanda.com/agentic-data-plane/gateway/code-mode/) - [Create an Agent](https://docs.redpanda.com/agentic-data-plane/connect/create-agent/)