# Client Features: Sampling, Roots, Elicitation, Pagination — MCP & Agent-to-Agent Protocols

Source: https://www.geekswithgeeks.com/en/mcp-a2a/m-client-features

> Know what a server can ask of the client, and how long lists are paged.

## Servers can ask back

MCP is not only client-to-server. A client can offer features the server may request, if the client declared them: **sampling** (the server asks the host to run an LLM completion on its behalf, so the server needs no model keys and the user stays in control and can approve), **roots** (the host tells the server which folders or URIs it may work within) and **elicitation** (the server asks the user for missing information through the host). Long lists such as `tools/list` use **cursor-based pagination**: the response includes a `nextCursor` to pass back until none remains. Because these flows let a server influence what the model sees and does, hosts should treat them as **requests**, show them to the user where appropriate, and enforce limits.

## Cursor pagination, run

I ran this with plain Python 3 (standard library only). Five items with a page size of 2 come back as three pages. The client keeps passing the returned cursor until `nextCursor` is `None`.

```python
def paginate(items, cursor=None, page_size=2):
    start = int(cursor) if cursor else 0
    chunk = items[start:start + page_size]
    nxt = str(start + page_size) if start + page_size < len(items) else None
    return {"items": chunk, "nextCursor": nxt}

tools = ["a", "b", "c", "d", "e"]
cursor, pages = None, []
while True:
    page = paginate(tools, cursor)
    pages.append(page["items"])
    cursor = page["nextCursor"]
    if cursor is None:
        break
print(pages)

```

Output:

```
[['a', 'b'], ['c', 'd'], ['e']]
```

**Quiz:** What does sampling let a server do?

- [ ] Skip authentication
- [ ] Read any file on disk
- [x] Ask the host to run an LLM completion, with the user in control
- [ ] Change the protocol version

*Answer:* Ask the host to run an LLM completion, with the user in control. The server borrows the client's model; the host can review and approve.