# MCP servers

> Connect tool servers and verify the Server-side network and process environment.

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LLMS index: [llms.txt](/llms.txt)

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MCP (Model Context Protocol) lets agents use tools from another service. An MCP server describes the operations it offers; AGW connects to it and makes those tools available to a custom agent. The available operations depend on the service.

Prepare the service’s launch command or URL, transport, and required credentials. The model itself is configured separately through a Model Provider.

## Connect

1. On the **MCP Tool Servers** page, click **Add Server**, choose `stdio` or `http` in **Transport Type**, and enter the command or endpoint and credentials the service requires.
2. Local-process servers must be launchable on the execution node; remote services must be reachable from that node.
3. Click **Connect and list tools** in the list to check connectivity; success shows “N tools available”. Make sure **Enabled** is on, because disabled servers are not used.
4. Bind the service in the **MCP Tool Server** tab of a custom agent or Project, then start a new turn. A run uses every server bound to the Agent and the Project.
5. Inspect discovered tools and validate a read-only operation.

Directories, commands, and network access belong to the actual Server/execution node. Connecting a remote Desktop does not automatically expose locally installed MCP services to the Server.

![AGW Desktop: configure a stdio MCP Server with its command, arguments, working directory, and required environment variables.](/images/screenshots/mcp-create.png)
{caption="AGW Desktop: configure a stdio MCP Server with its command, arguments, working directory, and required environment variables."}

## Choose a transport

| Transport | How it connects | What to check |
| --- | --- | --- |
| stdio | AGW starts a process and communicates through its input and output | The executable, arguments, and working directory exist on the execution host |
| http | AGW connects to an already running tool service. Choose `http` for SSE services too; AGW detects the HTTP transport the service uses | The URL and authentication are correct and reachable from the execution host |

A stdio command may work in your personal terminal but be unavailable to a Server running under another account or in a container. Check commands and environment variables in that environment. Test remote URLs from the execution host as well.

## Relationship to Integrations

MCP is a tool protocol. An Integration provides catalog definitions, user configuration, credentials, and a Connection lifecycle. Integrations can themselves expose tools through MCP.

Plugin MCP supports stdio, HTTP, and SSE sources. Plugin HTTP/SSE sources that inject credentials must use HTTPS. Credentials are resolved within the invocation scope; keep them out of public URLs and prompts.

## Troubleshoot

A server that cannot be reached at run time is skipped with a warning in the Server log, and the turn continues; an invalid or conflicting tool name fails the turn. When a stdio server starts, environment variables supplied by the execution override same-name values in the server configuration.

For missing tools, check bindings, launch commands, executables, network reachability, and credentials. Verify the service in the same execution environment before retrying a new agent turn. External CLI MCP configuration follows that tool's mechanism and is not AGW Connection injection.

## Implementation and references

- [Integrations and MCP](https://github.com/zxyao145/agw/blob/main/src/server/Agw.Integrations/README.md)
- [Agent execution](https://github.com/zxyao145/agw/blob/main/src/server/Agw.Agents.Execution/README.md)

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Backlinks:

- [User guide](/docs/guides/)
- [Tools and Skills](/docs/guides/tools-skills/)
- [Core concepts](/docs/start/concepts/)