How to Build an MCP Server That Serves SKILL.md Skills

MCP (Model Context Protocol) lets AI agents connect to external services and use them as tools. An MCP server that serves skills gives agents live access to a skill catalog — instead of downloading skills manually, the agent pulls the right skill automatically when it needs it.

This is how Agensi's one-liner curl install works. Here's how to build one yourself.

Quick Answer: An MCP skill server allows AI agents to dynamically search for and retrieve SKILL.md content at runtime instead of relying on manually downloaded files. It exposes search_skills and get_skill tools, facilitating on-demand access to a skill catalog.

What an MCP skill server does

A traditional skill workflow: developer downloads SKILL.md, puts it in a folder, agent reads it at startup.

An MCP skill server workflow: agent connects to MCP endpoint, searches for relevant skills at runtime, loads the skill content on demand. No downloads, no file management.

The MCP server exposes two main tools:

1. search_skills — takes a natural language query, returns matching skills
2. get_skill — takes a skill identifier, returns the full SKILL.md content

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Basic architecture

Agent (Claude Code) → MCP Connection → Your Server → Skill Database

The agent connects via Server-Sent Events (SSE) or stdio. When the user asks for help with a task, the agent queries your server for matching skills, reads the SKILL.md content, and applies it to the current task.

Setting up the server

Using the MCP SDK for TypeScript:

import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";

const server = new McpServer({
  name: "skill-server",
  version: "1.0.0"
});

// Tool: search for skills
server.tool("search_skills", {
  description: "Search for SKILL.md skills by task description",
  inputSchema: {
    type: "object",
    properties: {
      query: { type: "string", description: "What task do you need help with?" }
    },
    required: ["query"]
  }
}, async ({ query }) => {
  const results = await searchSkills(query);
  return {
    content: [{ type: "text", text: JSON.stringify(results) }]
  };
});

// Tool: get full skill content
server.tool("get_skill", {
  description: "Get the full SKILL.md content for a specific skill",
  inputSchema: {
    type: "object",
    properties: {
      skill_id: { type: "string", description: "Skill identifier" }
    },
    required: ["skill_id"]
  }
}, async ({ skill_id }) => {
  const content = await getSkillContent(skill_id);
  return {
    content: [{ type: "text", text: content }]
  };
});

Skill search implementation

The search tool needs to match natural language queries to skills. Options from simplest to most sophisticated:

Keyword matching: Search skill names and descriptions for query terms. Fast, simple, but misses semantic matches.

Embedding search: Generate vector embeddings of skill descriptions. Store in a vector database (pgvector, Pinecone, Qdrant). Find nearest neighbors to the query embedding. Catches semantic matches — "fix my tests" matches a skill described as "generates test files for uncovered functions."

Hybrid: Keyword search for exact matches, embedding search for semantic matches, combine and rank results.

Deployment

MCP servers can be deployed as:

• Cloud function (Netlify Edge, Vercel, AWS Lambda) — scales to zero, cheap
• Dedicated server — more control, needed for persistent connections
• Local process — for personal/development use

The server URL gets added to the agent's MCP configuration:

{
  "mcpServers": {
    "skill-server": {
      "url": "https://your-server.com/mcp"
    }
  }
}

Connecting to Agensi's catalog

Instead of building your own skill database, you can proxy to Agensi's catalog API. Agensi's public catalog API already serves the full marketplace catalog. Pro subscribers get live access to all skill content.

If you're building a custom server for your team, you might combine your private internal skills with Agensi's public catalog — search your team's skills first, fall back to the marketplace for skills you don't have internally.

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Connect to the Agensi skill catalog via MCP at Agensi's one-liner curl install.