import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
import { readFileSync, writeFileSync, mkdirSync } from 'node:fs';
import { dirname } from 'node:path';
import { z } from 'zod';
import type { Recipe } from './howto.js';
import { REPO_COOKBOOK_PATH } from './howto.js';
export function registerHowtoAddTool(server: McpServer): void {
server.registerTool(
'gerbil_howto_add',
{
title: 'Add Gerbil Cookbook Recipe',
description:
'Append a new Gerbil Scheme recipe to the gerbil-mcp cookbook. ' +
'If a recipe with the same id already exists, it is replaced (update semantics). ' +
'By default writes to the gerbil-mcp repo cookbook. ' +
'Optionally specify cookbook_path to write to a different file.',
inputSchema: {
cookbook_path: z
.string()
.optional()
.describe(
'Absolute path to a JSON cookbook file. If omitted, writes to the gerbil-mcp repo cookbook.',
),
id: z
.string()
.describe('Unique recipe identifier in kebab-case (e.g. "read-csv-file")'),
title: z.string().describe('Human-readable title (e.g. "Read a CSV file")'),
tags: z
.array(z.string())
.describe('Search keywords (e.g. ["csv", "file", "read", "parse"])'),
imports: z
.array(z.string())
.describe('Gerbil module imports (e.g. [":std/text/csv"]). Use [] if none needed.'),
code: z.string().describe('Code example'),
notes: z.string().optional().describe('Usage notes'),
related: z
.array(z.string())
.optional()
.describe('Related recipe IDs'),
},
},
async ({ cookbook_path: explicitPath, id, title, tags, imports, code, notes, related }) => {
const cookbook_path = explicitPath || REPO_COOKBOOK_PATH;
// Read existing file or start fresh
let recipes: Recipe[] = [];
try {
const raw = readFileSync(cookbook_path, 'utf-8');
const parsed = JSON.parse(raw);
if (!Array.isArray(parsed)) {
return {
content: [
{
type: 'text' as const,
text: `Error: ${cookbook_path} does not contain a JSON array.`,
},
],
isError: true,
};
}
recipes = parsed;
} catch (e: unknown) {
if ((e as NodeJS.ErrnoException).code === 'ENOENT') {
// File doesn't exist yet — start with empty array
recipes = [];
} else {
return {
content: [
{
type: 'text' as const,
text: `Error reading ${cookbook_path}: ${e instanceof Error ? e.message : String(e)}`,
},
],
isError: true,
};
}
}
// Build the new recipe
const recipe: Recipe = { id, title, tags, imports, code };
if (notes) recipe.notes = notes;
if (related && related.length > 0) recipe.related = related;
// Replace existing recipe with same id, or append
const existingIdx = recipes.findIndex((r) => r.id === id);
if (existingIdx >= 0) {
recipes[existingIdx] = recipe;
} else {
recipes.push(recipe);
}
// Write back
try {
mkdirSync(dirname(cookbook_path), { recursive: true });
writeFileSync(cookbook_path, JSON.stringify(recipes, null, 2) + '\n');
} catch (e: unknown) {
return {
content: [
{
type: 'text' as const,
text: `Error writing ${cookbook_path}: ${e instanceof Error ? e.message : String(e)}`,
},
],
isError: true,
};
}
const action = existingIdx >= 0 ? 'Updated' : 'Added';
return {
content: [
{
type: 'text' as const,
text: `${action} recipe "${id}" in ${cookbook_path} (${recipes.length} total recipes).`,
},
],
};
},
);
}
