# Mastra Tools Tools are [[Mastra AI]]'s structured wrappers that let [[Mastra Agents|agents]] do things models can't do alone, call external APIs, fetch data, perform actions. Each tool has a unique `id`, a description, an `inputSchema` and `outputSchema` (Zod / Valibot / ArkType), and an `execute` function. Typed schemas give the agent consistency and let Mastra validate calls. ## Key aspects - Schema-validated inputs/outputs for reliable tool calling - Tools can be exposed as or consumed from [[Model Context Protocol (MCP)|MCP]] servers - Composable with processors/guardrails for safety and cost control - Testable in isolation via [[Mastra Studio]] ## References - https://mastra.ai/docs/agents/using-tools ## Related - [[Mastra AI]] - [[Mastra Agents]] - [[Model Context Protocol (MCP)]] - [[Mastra Studio]]