How to Attach a Server

This guide walks through attaching a federated MCP server end to end. By the end you’ll have a server wired into your agent, play, or editor — with its trust tier and namespace applied.

1. Find the server

Open the marketplace and pick a server. Every listing shows its trust tier, install count, namespace, and the mcp.json blocks you’ll copy in the next step.

Prefer a verified or first-party server when one exists — it attaches without a trust prompt and its evidence is reviewable.

2. Choose how to attach

There are three ways to attach, from quickest to most governed:

Method	Best for	Trust policy applied
`mcp.json`	A single editor / client	When you use the federation form
`mcp_scope`	A solution play (whole team)	Always
VS Code deep link	One-click from the web	When the extension is installed

3a. Attach via `mcp.json`

On the server’s detail page, copy the FrootAI federation block (recommended):


{ "mcpServers": { "frootai": { "command": "npx", "args": ["-y", "frootai-mcp", "--attach", "<slug>"] } } }

This routes the upstream server through the federation router, so its tools are namespaced and the trust policy is enforced. The direct upstream block is also offered if you want to run the server without FrootAI in between.

3b. Attach via `mcp_scope` (plays)

For a solution play, declare the server in the play’s agent.md frontmatter so the engine auto-attaches it at activation time:


mcp_scope:
  attached: ["<slug>"]

The play’s mcp_scope.attached list is authoritative — the engine guarantees those servers are wired before the first agent turn. See cookbook recipe 20 — Author a Play with mcp_scope for the full walkthrough.

3c. Attach from VS Code

On the detail page, click Open in VS Code. The deep link (vscode://frootai.frootai-vscode/federation.attach?name=<slug>) hands the slug to the FrootAI extension, which attaches it for you. If the extension isn’t installed, the page links you to the Marketplace listing.

4. Provide credentials

If the server needs environment variables (an API token, a subscription id), the detail page lists every variable, whether it’s required, and the auth mode. Set the required variables before the first call — required ones are flagged in amber.

5. Handle the trust prompt

What happens on attach depends on the server’s tier:

First-party / Verified — attaches silently.
Community — you’ll be prompted to confirm; or declare a documented trust_overrides entry (cookbook recipe 22).
Untrusted — blocked at attach.

Next steps

What’s Federation? — why the router, namespacing, and trust tiers exist.
Trust Tiers — how publishers are classified and promoted.
Browse the marketplace — every federated server, ready to attach.