Understand and add MCP proxies

Add an MCP proxy to expose selected tools, prompts, and resources from an external MCP server through your Celigo MCP server.

For an introduction, see MCP proxies overview.

Prerequisites

• You must be an account owner or administrator.
• The Celigo MCP server must already exist.
• An MCP connection to the external MCP server must exist and be online.

Add an MCP proxy

1. Go to AI Studio > MCP servers, and select the MCP server.
2. On the Configuration tab, expand MCP proxies, and select + Add.
   
3. From Connection, select the MCP connection for the external MCP server. Celigo connects to the external MCP server and retrieves its available capabilities.
   Tip: Capabilities section is available only on selecting a connection.
4. Select Add capabilities.
5. Select the capabilities you want to expose. Use the Tools, Prompts, and Resources tabs to browse by type, or use Search to find a capability.
6. To add all capabilities of a type, select Select all.
7. Select Save.
8. Review the selected capabilities.
   
9. Select Save & close.

Celigo adds the selected capabilities to the MCP server and identifies them as Proxied.

Tip: If capabilities don't appear after you select a connection, verify that the MCP connection is online and that its credentials can access the external MCP server. See Troubleshoot an MCP proxy.

Add more capabilities

New capabilities published by the external MCP server aren't added automatically. To add them:

1. Open the MCP server.
2. On the Configuration tab, expand MCP proxies and open the proxy.
3. Select Add capabilities.
4. Select the additional capabilities.
5. Select Save, and then Save & close.

Add built-in capabilities

You can add your own Celigo Tools, APIs, Prompts, and Resources to an MCP server that also contains proxied capabilities. In Capabilities, select Add and add the resources as you would for any MCP server. End users see the built-in and proxied capabilities available to them through the same MCP server.

After you add an MCP proxy, its capabilities appear in the MCP server's Capabilities section. You can control their availability, customize how they appear to AI agents, manage end-user access, and handle capabilities added or removed by the external MCP server.

Prerequisites

• You must be an account owner or administrator.
• The MCP server must have at least one MCP proxy.

View proxied capabilities

1. Go to AI studio > MCP servers, and select the MCP server.
2. On the Configuration tab, go to Capabilities.
3. Select:
   • Built-in to view capabilities added from Celigo.
   • Proxied to view capabilities from external MCP servers.

A customized capability is marked Customized. A capability that the external MCP server no longer provides is marked Unavailable.

Use the toggle next to a capability to control its availability on the MCP server. Turning a capability off hides it from MCP clients and prevents it from being called, but doesn't remove it from the proxy.

Customize a proxied capability

You can override how an MCP client or AI agent sees a proxied capability without changing the capability on the external MCP server.

1. On the Proxied tab, open the settings for the capability.
2. Configure any supported overrides:
   • Name — The name displayed to MCP clients.
   • Description — Guidance that helps AI agents understand when and how to use the capability.
   • Annotations — Information that describes how the capability behaves.
3. Select Save.

Celigo marks the capability Customized.

To restore the external server's values, clear the overrides and save.

Note: If a proxied capability has the same name as another capability, Celigo adjusts its name to keep it unique. Adding a proxy can therefore rename a capability that end users already call, so update any agent that references the previous name. Set a Name override if you want to use a different name.

Control end-user access

Proxied Tools and Prompts use the same end-user access controls as supported built-in capabilities.

• Add proxied Tools to capability sets or grant them directly to end users or groups.
• Grant proxied Prompts directly to end users or groups. Prompts can't be included in capability sets.
• Resources don't have per-user grants. End users with access to the MCP server can access Resources that are turned on.

A capability that's turned off isn't available even when an end user has otherwise been granted access.

See Create and manage capability sets on MCP servers.

Add newly published capabilities

New capabilities published by the external MCP server aren't exposed automatically.

To add them:

1. Go to AI studio > MCP servers, and select the MCP server.
2. On the Configuration tab, expand MCP proxies, and open the proxy.
3. Select Add capabilities.
4. Select the capabilities you want to add, and select Save.
5. Select Save & close.

Manage unavailable capabilities

When the external MCP server stops providing a capability, Celigo marks it Unavailable. MCP clients can't see or call it, but Celigo retains its configuration.

• If the external server renamed or replaced the capability, add the new capability and remove the unavailable one.
• If the capability was removed permanently, remove it from the proxy when you no longer need it.
• If the external server restores the capability, it becomes available again with its previous settings.

Use this article when MCP proxy capabilities don't load, calls fail, capabilities become unavailable, or changes don't appear in your MCP client.

Capabilities don't load

If capabilities don't appear after you select an MCP connection:

1. Go to Resources > Connections and verify that the MCP connection is online.
2. Test the connection and verify its credentials.
3. Confirm that the connection points to the external server's MCP endpoint, using an http or https URL that resolves to a public address, Celigo blocks private, link-local, and cloud metadata addresses.
4. Confirm the external MCP server is reachable over HTTP. A server distributed only as a local package that runs on a user's machine can't be proxied.
5. Try loading the capabilities again.

A proxied call fails

Check the following:

1. Is the capability turned on? 
   On the Proxied tab, verify that the capability is enabled.
2. Does the end user have access? 
   Verify that the end user has access directly or through the applicable group or capability set.
3. Is the capability unavailable? 
   If it's marked Unavailable, the external MCP server no longer provides it. See Manage proxied capabilities.
4. Did authentication fail? 
   Check the request log. If the external server rejects the MCP connection's credentials, update or reauthenticate the connection.
5. Did the call exceed a traffic limit? 
   A Celigo traffic-limit rejection returns an HTTP 429 response. If the external MCP server applies its own rate limit, the request log identifies the failure as a rate-limit error. See Monitor requests that exceed MCP server traffic limits.
6. Did the request time out? 
   A proxied call times out after 60 seconds, or sooner if the MCP connection sets a shorter timeout. Check whether the external MCP server responded within that window.
7. Is the external MCP server available? 
   If the external server is unavailable, proxied capabilities can fail while built-in capabilities on the Celigo MCP server continue working.

A capability is unavailable

An Unavailable capability is one that the external MCP server no longer provides. Check whether the external provider renamed or replaced the capability. If a replacement is available, add it from Add capabilities and remove the unavailable capability when appropriate. If the external server restores the original capability, Celigo makes it available again with its previous configuration.

A client doesn't show a capability

If an enabled capability doesn't appear in an MCP client:

1. Refresh the client's capabilities or restart the session.
2. Verify that the capability is turned on.
3. Verify that the end user has access to it.

An agent uses the wrong capability

If similar capability names cause an AI agent to select the wrong capability, customize the capability's Name or Description to make its purpose clearer. See Manage proxied capabilities.

A capability name changed

Celigo adjusts a proxied capability's name to <alias>_<name> when another capability with the same name is added. If an agent references the previous name, update the agent or customize the proxied capability's name.