agent-mcp-builder git:20261014.522e28aA

Immutable. This exact content never changes and is served at /api/v1/blob/b419851e9d3f921b.

---
name: agent-mcp-builder
description: "Builds MCP servers, tools, resources and prompts with strict JSON schemas, stdio or SSE transports and error boundaries. Use for 'build an MCP server' or 'expose this API as MCP tools'."
---

# Agent & MCP Builder

## Overview

The Model Context Protocol (MCP) provides a standardized protocol for AI models and agents to interact with external tools, databases, APIs, and file systems. `agent-mcp-builder` establishes best practices for building, debugging, and maintaining MCP servers in TypeScript/Node.js and Python.

## Core Architecture

### 1. Transports & Protocols
- **stdio Transport**: Standard input/output for local desktop applications, CLI agents, and IDE extensions.
- **SSE (Server-Sent Events) Transport**: Over HTTP for remote, cloud-hosted MCP services.

### 2. Tools Definition Standard
- Strict JSON Schema parameter definitions with descriptive parameter instructions.
- Clear tool names and human-readable summaries.
- Return structured content blocks (`{ type: "text", text: "..." }` or `{ type: "image", ... }`).

### 3. Error Handling in MCP Tools
- Never crash the MCP server process on tool execution errors.
- Catch internal exceptions and return informative error payloads so the agent can self-correct:
  ```json
  {
    "isError": true,
    "content": [{ "type": "text", "text": "Error: Database connection timed out. Verify DB_HOST configuration." }]
  }
  ```

### 4. Lazy vs. Eager Tool Registration
- For large catalogs (> 10 tools), register tools lazily with lightweight schema manifests to prevent bloating the model's initial context window.