MCP
The MCP server lets AI assistants such as Claude, ChatGPT, and Cursor read and update your work.
Endpoint and authentication
Clients that ask for a server URL use the hosted endpoint:
https://mcp.onehorizon.ai/mcpFor Cursor, One Horizon Desktop can add this server to your user-level ~/.cursor/mcp.json file. Existing servers stay unchanged.
The button opens One Horizon Desktop to review and finish the change. If Desktop is not installed, the dialog links to the download. The Cursor integration guide also keeps the direct Install with Cursor option.
Authentication uses OAuth 2.0. Public clients use PKCE directly, so most MCP clients do not need a client ID or client secret. The assistant acts with the workspace access of the person who connects it.
For backend services and CI jobs, use the REST API instead.
What assistants can do
| Capability | Examples |
|---|---|
| Read work | Planned work, completed work, blockers, initiatives, bugs, task details and comments, teams, members, workspaces, taxonomy, and search. |
| Create and update work | Initiatives, bugs, feature requests, todos, comments, and reactions. |
| Documents | Find, read, create, update, link, and delete workspace documents. |
| Pull requests | List, open, and update pull requests and merge requests. |
| Workflows and agents | List agents and capabilities; create, validate, publish, and start workflows; approve, reject, reassign, or send feedback on workflow reviews. |
The assistant writes summaries, standup notes, and handoff notes itself from what these tools return.
Typical requests: "Show my planned work for this week", "What's blocking the frontend team?", or "Capture this as completed work."
To hand implementation to an agent, use Send to Agents.
Task and workflow run cards
In clients that support MCP Apps, two tools show results as interactive cards instead of plain text. The assistant calls them with IDs returned by other tools, so asking to see your tasks or follow a run is enough.
| Tool | What the card shows |
|---|---|
show-tasks | Up to 20 tasks, including initiatives, bugs, and todos. Each row is clickable and shows the title, status, assignees, and a badge for an active workflow run that opens the run, plus an icon-only link to open the task in One Horizon. |
show-workflow-runs | Up to 10 workflow runs. Each card shows the run status, completed and total steps, the current step, its latest activity, what is waiting for review, and an icon-only link to open the run in One Horizon. |
Run cards offer only the actions valid for that run and the signed-in user: Approve, Request changes, Continue, and Cancel run. If the run changed after the card loaded, the card shows the current state instead of applying the action. Active runs refresh while the card is visible and stop refreshing once the run finishes.
Clients without MCP Apps support get the same items as text, with a URL: line for each item and a list of IDs that were not found or not accessible. If a client renders cards but does not let them call tools, the cards are read-only.
The card never receives your One Horizon credentials. Every refresh and action goes through your MCP connection and is authorized again on the server.
Pull requests and merge requests
Three tools work with GitHub, GitLab, and Bitbucket:
| Tool | What it does |
|---|---|
list-pull-requests | Lists pull requests or merge requests visible to the signed-in member. Filter by provider, repository, or lifecycle status. |
create-pull-request | Opens a pull request or merge request using the member's stored provider token. The head branch must already exist on the remote. |
update-pull-request | Edits title or body, closes or reopens, and adds or removes reviewers, assignees, and labels where the provider supports them. |
Repository access follows the connected OAuth grant for each provider. Reviewer identifiers follow provider conventions: GitHub usernames, GitLab numeric user IDs as strings, and Bitbucket account UUIDs. Bitbucket does not support labels or assignees on pull requests, and declined Bitbucket pull requests cannot be reopened through the API.
Client setup
| Client | Setup notes |
|---|---|
| ChatGPT | Requires ChatGPT Plus or higher with Developer Mode enabled. Add a custom app in ChatGPT Apps with the One Horizon MCP endpoint and OAuth authentication. Developer Mode currently works in regular chats, not Project chats or Deep Research. |
| Claude Code | Add the server with claude mcp add --transport http onehorizon https://mcp.onehorizon.ai/mcp, or import it from Claude Desktop with claude mcp add-from-claude-desktop --scope user. Use /mcp inside Claude Code to inspect connected servers. |
| Claude Desktop | Add a remote HTTP MCP server named onehorizon, authenticate through the OAuth prompt, then start a new conversation before using tools. |
| Cursor, Windsurf, JetBrains IDEs, and Codex | Add the MCP server from the tool's MCP settings and authenticate through the browser. If the tool supports project-level MCP config, keep workspace-specific setup in the project config. |
| n8n and automation clients | MCP fits assistant-style tool calls. For flows that react to workspace events, use Webhooks. |
If a client supports both a user-level and project-level MCP configuration, choose user-level for personal work context and project-level when the connection should travel with a repository.
Access rules
The assistant cannot see or change workspaces, teams, documents, or tasks the signed-in user cannot access. Team IDs passed to create or update tools are checked against the teams the user can access.