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Connect an agent

Use Horison from Claude, ChatGPT, Cursor, or any client that speaks MCP.

Horison runs a hosted MCP server. Your client signs in as you. It can read the deals, documents, and firm memory your Horison account can see, and nothing else.

The same steps live in the app under Settings → Integrations → Connect your agent, with copy buttons. This page is the shareable URL. Clients can fetch a Markdown version at /agents.md.

Two different agents

Agents on the rail run inside Horison and leave you a memo or a screen. This page is the other direction: Claude or ChatGPT running outside, calling into Horison as you. They share your workspace. They do not share a screen or a tool list. Attio’s CRM tools stay in Horison Chat and Horison Agents. They are not on this server.

Server URL

https://mcp.horison.ai/mcp

The client talks over streamable HTTP. Sign-in is OAuth: the client opens a Horison page in the browser. There is no API key to paste.

In the app: Settings → Integrations → Connect your agent.

Claude (claude.ai / Desktop / Cowork)

  1. 01

    Open connector settings

    Settings → Connectors → Add custom connector.

  2. 02

    Paste the server URL

    https://mcp.horison.ai/mcp

  3. 03

    Approve the connection

    Sign in on the Horison consent page. Horison tools then appear in the client.

  4. 04

    Skip the prompt on every call (recommended)

    In the connector settings, switch Horison tools from Needs approval to Always allow.

Claude Code

claude mcp add --scope project --transport http horison-ai https://mcp.horison.ai/mcp

Then run /mcp, select horison-ai, and choose Authenticate.

ChatGPT

  1. 01

    Turn on developer mode

    Settings → Apps → Advanced settings → turn on Developer mode.

  2. 02

    Add the connector

    Settings → Apps → Create. Paste https://mcp.horison.ai/mcp and choose OAuth.

  3. 03

    Approve the connection

    Sign in on the Horison consent page.

Cursor, VS Code, and other clients

Most MCP clients accept:

{
  "mcpServers": {
    "horison-ai": {
      "type": "http",
      "url": "https://mcp.horison.ai/mcp"
    }
  }
}

Authenticate the first time you connect.

What it can access today

Access is limited to what your Horison account can see. The client cannot see another person or another firm. Turning MCP on for the workspace is the gate. There is no separate “graph only” switch yet.

Read

  • Deals: list them, open an overview, compare something across deals.
  • Graph: search, entity details, related entities, metric history, themes.
  • Documents: list files, read a document, insights, suggested questions, evidence.
  • Firm memory: claims, decisions, criteria, firm-level search.
  • People: your private contacts, and the signed-in profile.

Write (narrow)

  • Propose a relationship, then confirm it. Confirmation is an approval you give.
  • List, read, and create skills. Creating a skill needs an explicit yes.

Those two writes are the only writes against firm data. This is not Attio’s CRM toolkit, and it cannot start an in-product agent yet.

What is coming

Trigger an agent from the client

The next step for this server is to start an in-product agent (a memo, a screen, or one you have written) and to retrieve the result once it finishes. That is not on the server today. Until it ships, run those jobs from Agents in Horison, and use this connection to read the graph and the documents.

Skills

Optional PE skills (IC memos, a diligence gap pass, a deal comparison) live at github.com/horison-ai/agent-skills. Install with npx skills add horison-ai/agent-skills.

Firm admin

A workspace admin has to turn MCP on under Settings before anyone can connect a client. The default is off. The first time they enable it, they accept the MCP terms. Turning it off takes about a minute to stick. There is no separate switch for the two write tools above. That is the shape of the server.

Admins can require approval before a colleague’s client is admitted, or leave connections open.

If something fails

  • Sign-in loops: remove the Horison connector, add it again, and finish sign-in in one pass.
  • Unauthorized: the client is not signed in yet. Run Authenticate again. In Claude Code: /mcp → horison-ai → Authenticate.
  • It worked before and now fails: the session expired. Sign in again.
  • A new skill has no slash command: slash commands load at session start. Asking the client to read the skill still works immediately.
  • Tenant has not enabled MCP: an admin has to turn it on under Settings before the consent page will let you in.
Need the in-app copy buttons? Open Connect your agent.
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