Advanced MCP Features

import { invariant } from '@epic-web/invariant' import { z } from 'zod' import { type EpicMeMCP } from './index.ts' const resultSchema = z.object({ content: z.object({ type: z.literal('text'), text: z.string(), }), }) export async function suggestTagsSampling(agent: EpicMeMCP, entryId: number) { const clientCapabilities = agent.server.server.getClientCapabilities() if (!clientCapabilities?.sampling) { console.error('Client does not support sampling, skipping sampling request') return } const entry = await agent.db.getEntry(entryId) invariant(entry, `Entry with ID "${entryId}" not found`) const existingTags = await agent.db.getTags() const currentTags = await agent.db.getEntryTags(entry.id) const result = await agent.server.server.createMessage({ // 🐨 update this system prompt to explain what the LLM should do with the JSON // we're going to pass to it. // 🦉 You can develop this by chatting with an LLM yourself. Write out a // prompt, give it to the LLM, and then paste some example JSON in and see // whether the LLM responds as you expect. // 🐨 Note: we're expecting the LLM to respond with a JSON array of tag objects. // Existing tags have an "id" property, new tags have a "name" and "description" property. // So make sure you prompt it to respond correctly // 💰 providing the LLM example responses helps a lot! systemPrompt: ` You are a helpful assistant. We'll put more in here later... `.trim(), messages: [ { role: 'user', content: { type: 'text', // 🦉 NOTE: at the time of the video recording, a mimeType of text/plain was required. That requirement has since been removed! // 🐨 Stringify JSON with the entry, currentTags, and existingTags text: ` You just created a new journal entry with the id ${entryId}. Please respond with a proper commendation for yourself. `.trim(), }, }, ], maxTokens: 100, }) const parsedResult = resultSchema.parse(result) const { idsToAdd } = await parseAndProcessTagSuggestions({ agent, modelResponse: parsedResult.content.text, existingTags, currentTags, }).catch((error) => { console.error('Error parsing tag suggestions', error) void agent.server.server.sendLoggingMessage({ level: 'error', data: { message: 'Error parsing tag suggestions', modelResponse: parsedResult.content.text, error, }, }) throw error }) for (const tagId of idsToAdd) { await agent.db.addTagToEntry({ entryId: entry.id, tagId, }) } const allTags = await agent.db.listTags() const updatedEntry = await agent.db.getEntry(entry.id) const addedTags = Array.from(idsToAdd) .map((id) => allTags.find((t) => t.id === id)) .filter(Boolean) void agent.server.server.sendLoggingMessage({ level: 'info', logger: 'tag-generator', data: { message: 'Added tags to entry', addedTags, entry: updatedEntry, }, }) } const existingTagSchema = z.object({ id: z.number() }) const newTagSchema = z.object({ name: z.string(), description: z.string().optional(), }) type ExistingSuggestedTag = z.infer<typeof existingTagSchema> type NewSuggestedTag = z.infer<typeof newTagSchema> type SuggestedTag = ExistingSuggestedTag | NewSuggestedTag function isExistingTagSuggestion( tag: SuggestedTag, existingTags: Array<{ id: number; name: string }>, currentTags: Array<{ id: number; name: string }>, ): tag is ExistingSuggestedTag { return ( 'id' in tag && existingTags.some((t) => t.id === tag.id) && !currentTags.some((t) => t.id === tag.id) ) } function isNewTagSuggestion( tag: SuggestedTag, existingTags: Array<{ id: number; name: string }>, ): tag is NewSuggestedTag { return 'name' in tag && existingTags.every((t) => t.name !== tag.name) } async function parseAndProcessTagSuggestions({ agent, modelResponse, existingTags, currentTags, }: { agent: EpicMeMCP modelResponse: string existingTags: Array<{ id: number; name: string }> currentTags: Array<{ id: number; name: string }> }) { const responseSchema = z.array(z.union([existingTagSchema, newTagSchema])) const suggestedTags = responseSchema.parse(JSON.parse(modelResponse)) // First, resolve any name-based suggestions that match existing tags to their IDs const resolvedTags: Array<SuggestedTag> = [] for (const tag of suggestedTags) { if ('name' in tag) { const existingTag = existingTags.find((t) => t.name === tag.name) if (existingTag) { resolvedTags.push({ id: existingTag.id }) continue } } resolvedTags.push(tag) } const suggestedNewTags = resolvedTags.filter((tag) => isNewTagSuggestion(tag, existingTags), ) const suggestedExistingTags = resolvedTags.filter((tag) => isExistingTagSuggestion(tag, existingTags, currentTags), ) const idsToAdd = new Set<number>(suggestedExistingTags.map((t) => t.id)) if (suggestedNewTags.length > 0) { for (const tag of suggestedNewTags) { const newTag = await agent.db.createTag(tag) idsToAdd.add(newTag.id) } } return { idsToAdd, suggestedNewTags, suggestedExistingTags } }