RAGmonsters Custom PostgreSQL MCP Server

Instructions

Implementation Reference

• src/mcp-server/tools/monsters.js:132-289 (handler)

  The core handler function for the getMonsterById tool. It queries the database for monster details by ID, retrieves associated abilities, keywords, flaws, strengths, and weaknesses, formats them into a structured JSON response, and returns it in the expected MCP content format.
  export async function getMonsterById(params) { try { if (!dbPool) { throw new Error('Database pool not initialized. Call initialize() first.'); } logger.info(`getMonsterById called with params: ${JSON.stringify(params)}`); const { monsterId } = params; if (!monsterId) { logger.error('Monster ID is required but was not provided'); throw new Error('Monster ID is required'); } logger.debug(`Fetching monster with ID: ${monsterId}`); // Get basic monster information const monsterQuery = ` SELECT m.* FROM monsters m WHERE m.monster_id = $1 `; const monsters = await executeQuery(dbPool, monsterQuery, [monsterId]); if (monsters.length === 0) { throw new Error(`Monster with ID ${monsterId} not found`); } const monster = monsters[0]; // Get monster's abilities and keywords const abilitiesQuery = ` SELECT k.keyword_name, k.rating, a.ability_name, a.mastery_value FROM questworlds_stats qs JOIN keywords k ON qs.stats_id = k.stats_id JOIN abilities a ON k.keyword_id = a.keyword_id WHERE qs.monster_id = $1 ORDER BY k.keyword_name, a.ability_name `; const abilities = await executeQuery(dbPool, abilitiesQuery, [monsterId]); // Get monster's flaws const flawsQuery = ` SELECT f.flaw_name, f.rating FROM questworlds_stats qs JOIN flaws f ON qs.stats_id = f.stats_id WHERE qs.monster_id = $1 ORDER BY f.rating DESC `; const flaws = await executeQuery(dbPool, flawsQuery, [monsterId]); // Get monster's strengths (augments) const strengthsQuery = ` SELECT target_name, modifier FROM augments WHERE monster_id = $1 `; const strengths = await executeQuery(dbPool, strengthsQuery, [monsterId]); // Get monster's weaknesses (hindrances) const weaknessesQuery = ` SELECT target_name, modifier FROM hindrances WHERE monster_id = $1 `; const weaknesses = await executeQuery(dbPool, weaknessesQuery, [monsterId]); // Organize abilities by keyword const keywordAbilities = {}; abilities.forEach(item => { if (!keywordAbilities[item.keyword_name]) { keywordAbilities[item.keyword_name] = { name: item.keyword_name, rating: item.rating, abilities: [] }; } keywordAbilities[item.keyword_name].abilities.push({ name: item.ability_name, mastery: item.mastery_value }); }); // Format the response return { content: [{ type: 'text', text: JSON.stringify({ id: monster.monster_id, name: monster.name, category: monster.category, habitat: monster.habitat, rarity: monster.rarity, discovery: monster.discovery, physicalAttributes: { height: monster.height, weight: monster.weight, appearance: monster.appearance }, powers: { primary: monster.primary_power, secondary: monster.secondary_power, special: monster.special_ability }, keywords: Object.values(keywordAbilities), flaws: flaws.map(flaw => ({ name: flaw.flaw_name, rating: flaw.rating })), strengths: strengths.map(strength => ({ target: strength.target_name, modifier: strength.modifier })), weaknesses: weaknesses.map(weakness => ({ target: weakness.target_name, modifier: weakness.modifier })) }) }] }; } catch (error) { logger.error(`Error in getMonsterById: ${error.message}`); logger.error(error.stack); throw new Error(`Failed to retrieve monster details: ${error.message}`); } }
• src/mcp-server/tools/index.js:38-45 (registration)

  The registration of the getMonsterById tool with the MCP server using server.addTool(). Includes the tool name, description, input schema using Zod (requiring a numeric monsterId), and binds the execute function to the imported getMonsterById handler.
  server.addTool({ name: 'getMonsterById', description: 'Get detailed information about a specific monster by ID', parameters: z.object({ monsterId: z.number().describe('ID of the monster to retrieve') }), execute: getMonsterById });
• src/mcp-server/tools/index.js:41-43 (schema)

  Zod schema definition for the getMonsterById tool input parameters, specifying that monsterId must be a number.
  parameters: z.object({ monsterId: z.number().describe('ID of the monster to retrieve') }),