What are MCPs and Why Do They Matter?
MCPs — Model Context Protocol servers — are the bridge between the Cosine CLI and external services like Notion, PostHog, Attio, Slack, and many others. Once configured, they let your agent pull live data from those tools directly during a task.
What MCPs Do
Section titled “What MCPs Do”Without an MCP, your agent only has access to what’s on your local disk and what it can find on the web. With an MCP, it can:
- Pull pages from your Notion workspace
- Query your CRM for customer data
- Read analytics events from PostHog
- Access records from any connected service
Think of it as giving your agent read access (and sometimes write access) to the tools you already use.
MCPs vs. APIs
Section titled “MCPs vs. APIs”You might wonder: if these services have APIs, why use MCPs instead?
| API | MCP |
|---|---|
| Requires documentation for the agent to know what endpoints exist | The agent can self-discover what data is available |
| Breaks if the service updates its API structure | The service updates the MCP; your agent adapts automatically |
| You need to write or find the integration yourself | A standardised protocol — just point the agent at the MCP |
In other words, MCPs are a self-describing API layer. The agent can ask the MCP “what can I access here?” and it gets back a full list of capabilities — no documentation required.
This is also why MCP adoption benefits service providers: they can update what they expose without breaking existing integrations.
How Authentication Works
Section titled “How Authentication Works”Many MCPs require authentication — you need to log in to the service before the agent can access it. This typically uses OAuth (the same “sign in with Google” flow you see on many websites).
The process:
- Configure the MCP in the CLI (see Setting Up MCPs).
- Open the MCP entry in the CLI’s MCP panel and press Enter.
- A browser window opens asking you to grant access.
- Once you approve, the CLI stores the credentials and the MCP is ready to use.
You only need to do this once per service. After that, the agent can use the MCP automatically in any session where it’s available.
MCP Scope: Global, Not Per-Folder
Section titled “MCP Scope: Global, Not Per-Folder”Unlike agent.md (which is folder-level), MCP configurations are global. They’re stored in ~/.cosine/mcp.json. An MCP you configure in one session is available across all your sessions and all your folders. See the MCP Configuration reference for the full config format and available options.
Key Takeaways
Section titled “Key Takeaways”- MCPs connect the Cosine CLI to external services like Notion, PostHog, Attio, and more.
- They give the agent the ability to self-discover available data — no documentation needed.
- Authentication is typically OAuth — a one-time setup per service.
- MCP config is global, not per-folder.