> ## Documentation Index
> Fetch the complete documentation index at: https://skybridge-staging-feat-register-resource-prompt.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Register Prompts

> Ship reusable prompts users can invoke

A **prompt** is the third MCP server primitive, alongside [tools](/build/tools) and [resources](/build/resources). It's a named, parameterized message template the user picks from the host's prompt menu; your handler returns the messages the host drops into the conversation. Use it to ship canned starting points, "Summarize this trip", "Draft a reply", so users don't retype them.

```ts server.ts theme={null}
import { McpServer } from "skybridge/server";
import { z } from "zod";

const server = new McpServer({ name: "travel", version: "1.0" }).registerPrompt(
  {
    name: "trip-summary",
    title: "Trip summary",
    description: "Summarize a trip to a destination.",
    argsSchema: { destination: z.string() },
  },
  ({ destination }) => ({
    messages: [
      {
        role: "user",
        content: { type: "text", text: `Summarize a trip to ${destination}.` },
      },
    ],
  }),
);
```

[`registerPrompt`](/api-reference/register-prompt) returns the server, so it chains next to your other registrations. `argsSchema` is a [Zod](https://zod.dev/) shape: it validates the arguments the host passes and types the handler's input.

<Info>
  Register prompts up front, at startup. Adding or removing them at runtime relies on `list_changed` notifications, which the stateless JSON transport can't deliver, so hosts won't see the change.
</Info>

## Completions

Wrap an argument in `completable()` to autocomplete it as the user fills in the prompt:

```ts server.ts theme={null}
import { completable } from "@modelcontextprotocol/sdk/server/completable.js";
import { z } from "zod";

server.registerPrompt(
  {
    name: "trip-summary",
    argsSchema: {
      destination: completable(z.string(), async (value) =>
        (await matchCities(value)).slice(0, 20),
      ),
    },
  },
  ({ destination }) => ({
    messages: [
      {
        role: "user",
        content: { type: "text", text: `Summarize a trip to ${destination}.` },
      },
    ],
  }),
);
```

The completion callback receives what the user has typed and returns the candidate values.

## Go Further

<Columns cols={3}>
  <Card title="registerPrompt" icon="message-square" href="/api-reference/register-prompt">
    Full config and handler reference
  </Card>

  <Card title="Register Resources" icon="file-text" href="/build/resources">
    Expose readable content
  </Card>

  <Card title="Register Tools" icon="wrench" href="/build/tools">
    The action primitive
  </Card>
</Columns>