Sometimes there are common workflows for people using your MCP server you want to make easier for users. You may not want your users to have to write the same prompt all the time for that workflow (not everyone is a "prompt engineer").
The Model Context Protocol (MCP) has a specification for prompts as a way for servers to expose reusable, structured instructions to language models and clients. Prompts are more than just static text—they can be parameterized and invoked by users to guide model behavior in a consistent, transparent way.
With prompts, servers can offer a menu of available instructions (like "summarize my journal entries from last week," "write alt text for this image" or "review this code"), each with a clear description and customizable arguments. This enables richer, more user-driven interactions, where clients can select and fill in prompts as needed.
import { invariant } from '@epic-web/invariant'
import { completable } from '@modelcontextprotocol/sdk/server/completable.js'
import { z } from 'zod'
import { type EpicMeMCP } from './index.ts'export async function initializePrompts(agent: EpicMeMCP) {agent.server.registerPrompt('suggest_tags',{title: 'Suggest Tags',description: 'Suggest tags for a journal entry',argsSchema: {entryId: completable(z.string().describe('The ID of the journal entry to suggest tags for'),async (value) => {const entries = await agent.db.getEntries()return entries.map((entry) => entry.id.toString()).filter((id) => id.includes(value))},),},},async ({ entryId }) => {invariant(entryId, 'entryId is required')const entryIdNum = Number(entryId)invariant(!Number.isNaN(entryIdNum), 'entryId must be a valid number')const entry = await agent.db.getEntry(entryIdNum)invariant(entry, `entry with the ID "${entryId}" not found`)const tags = await agent.db.listTags()return {messages: [{role: 'user',content: {type: 'text',text: `
Below is my EpicMe journal entry with ID "${entryId}" and the tags I have available.Please suggest some tags to add to it. Feel free to suggest new tags I don't have yet.For each tag I approve, if it does not yet exist, create it with the EpicMe "create_tag" tool. Then add approved tags to the entry with the EpicMe "add_tag_to_entry" tool.`.trim(),},},{role: 'user',content: {type: 'resource',resource: {uri: 'epicme://tags',mimeType: 'application/json',text: JSON.stringify(tags),},},},{role: 'user',content: {type: 'resource',resource: {uri: `epicme://entries/${entryId}`,mimeType: 'application/json',text: JSON.stringify(entry),},},},],}},)
}