build-mcp-server

What it is

build-mcp-server is the entry point for MCP server development in the mcp-server-dev plugin. It triggers when a user asks to "build an MCP server", "create an MCP", "wrap an API for Claude", "expose tools to Claude", "make an MCP app", or otherwise discusses building with the Model Context Protocol. Its core principle is "discovery, not code": picking the wrong server shape early causes painful rewrites later. Before giving guidance, it fetches https://claude.com/docs/llms-full.txt so its advice reflects Claude-specific auth types, review criteria and limits, which go beyond the generic MCP spec. The workflow runs in phases. Phase 1 asks five questions in a single batched message: what the server connects to, who will use it, how many distinct actions it exposes, whether a tool needs mid-call user input or rich display, and what auth the upstream service uses. Phase 2 recommends one deployment model. A remote streamable-HTTP server is the default recommendation. The alternatives are elicitation for simple structured input, an MCP app for interactive UI widgets, MCPB for bundled local servers, and local stdio (npx/uvx), which is only suggested for personal tools and prototypes. Phase 3 picks a tool-design pattern. Pattern A gives one tool per action for small surfaces (under about 15 operations). Pattern B uses search + execute for large APIs so the context window stays lean. A hybrid promotes the 3–5 most-used actions to dedicated tools. Phase 4 recommends a framework: either the official TypeScript SDK (@modelcontextprotocol/sdk) or FastMCP 3.x for Python. Phase 5 scaffolds inline for remote HTTP without UI or for local stdio prototypes. For MCP apps it hands off to the build-mcp-app skill, and for MCPB it hands off to build-mcpb, restating the design brief so the next skill doesn't re-ask. The skill also covers the other server primitives (Resources, Prompts, Elicitation, Sampling) and includes a quick-reference decision matrix. Phase 6 covers testing and publishing: adding the server as a custom connector in Claude, running the pre-submission checklist, submitting to the Anthropic Directory, and shipping a plugin that wraps the MCP with skills. Supporting reference files cover remote HTTP scaffolding, Cloudflare Workers deployment, tool design, auth (OAuth, CIMD, DCR), resources and prompts, elicitation, server capabilities, and version-sensitive claims.

Who it's for

• Developers building an MCP server that works with Claude
• Developers wrapping a cloud API (SaaS, REST, GraphQL) for Claude
• Developers who need a local server that touches files, desktop apps or OS-level APIs
• Developers planning to submit a connector to the Anthropic Directory

Requirements

Examples

build an MCP server

wrap an API for Claude

create_issue    — Create a new issue. Params: title, body, labels[]
update_issue    — Update an existing issue. Params: id, title?, body?, state?
search_issues   — Search issues by query string. Params: query, limit?
add_comment     — Add a comment to an issue. Params: issue_id, body

search_actions  — Given a natural-language intent, return matching actions
                  with their IDs, descriptions, and parameter schemas.
execute_action  — Run an action by ID with a params object.