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Overview

The Model Context Protocol (MCP) is an open standard that lets AI agents interact with external tools and services through a unified interface. Aster Agents supports connecting to any remote MCP server, giving your agents access to thousands of third-party tools without custom integration work. When an agent has MCP servers assigned, it automatically discovers and can call all tools provided by those servers during conversations.

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Features

  • Any Remote Server: Connect to any MCP server hosted on the internet by URL
  • Two Transports: Streamable HTTP (recommended) and Server-Sent Events (SSE)
  • Auth Headers: Pass API keys or Bearer tokens via custom headers
  • Auto-Discovery: Agent automatically discovers available tools at chat time
  • Multi-Server: Assign multiple MCP servers to a single agent
  • Organization-Level: Configure servers once, assign to any agent

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Prerequisites

  • An MCP server URL (hosted by a third party or self-hosted)
  • Any required authentication credentials (API key, Bearer token, etc.)
  • Admin access to your Aster Agents organization

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Setup Guide

1

Add an MCP Server

Navigate to Control Hub > Integrations and scroll down to MCP Servers. Click Add Server.
2

Configure the Server

Fill in the server details:
  • Name: A display name (e.g. “Hugging Face”, “Cloudflare Docs”)
  • Transport: Choose Streamable HTTP (recommended) or SSE
  • URL: The server’s MCP endpoint URL
  • Headers (optional): Add authentication headers (e.g. Authorization: Bearer your-api-key)
3

Test the Connection

After adding the server, click the play button on the server card to test connectivity. A successful test will report how many tools were discovered.
4

Assign to an Agent

Go to Control Hub > Agents, edit an agent, and scroll to the MCP Servers section. Check the servers you want this agent to use.

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Transport Types

TransportBest ForHow It Works
Streamable HTTPProduction (recommended)Uses HTTP POST for requests and optional SSE for streaming responses. Most reliable for serverless environments.
SSELegacy serversUses Server-Sent Events for bidirectional communication. Supported by older MCP server implementations.
If the server documentation doesn’t specify, try Streamable HTTP first.

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Example: Public MCP Servers

Many services now offer hosted MCP servers you can connect directly:
ServerURLTransportAuth
Hugging Facehttps://hf.co/mcpHTTPNone
Cloudflare Docshttps://docs.mcp.cloudflare.com/sseSSENone
Check awesome-remote-mcp-servers on GitHub for a community-maintained list of public MCP servers.

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How It Works at Runtime

When a user sends a message to an agent with MCP servers:
  1. Connect — Aster opens a connection to each assigned MCP server
  2. Discover — Tools are fetched from the server via the MCP protocol
  3. Merge — MCP tools are combined with the agent’s built-in tools
  4. Execute — The AI model can call any MCP tool during the conversation
  5. Cleanup — Connections are closed after the response completes
MCP tools appear alongside built-in tools from the model’s perspective. The agent decides which tools to use based on the conversation context.

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Security

  • Headers are encrypted — Auth headers are stored securely and redacted ([REDACTED]) in API responses
  • Organization-scoped — Only admins can add or modify MCP servers
  • Per-agent assignment — Each agent only accesses the servers explicitly assigned to it
  • No outbound data — Aster only sends tool call parameters to MCP servers, never conversation history

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Troubleshooting

  • Verify the URL is correct and the server is running
  • Check that you selected the right transport type (HTTP vs SSE)
  • Ensure any required auth headers are included
  • Try the URL in a browser to confirm it’s accessible
  • The server may be running but has no tools registered
  • Check the server’s documentation for setup requirements
  • Some servers require authentication before exposing tools
  • Check that auth credentials haven’t expired
  • Verify the server supports the parameters the model is sending
  • Review the conversation for error messages in tool results
  • Confirm the MCP server is assigned to the agent in Control Hub
  • Ensure the server is enabled (toggle on the server card)
  • Try prompting the agent to explicitly use a specific tool by name