frontmcp-extensibility

FrontMCP Extensibility

Patterns and examples for extending FrontMCP servers with external npm packages. The core SDK handles MCP protocol, DI, and lifecycle — this skill shows how to integrate third-party libraries as providers and tools.

When to Use This Skill

Must Use

• Adding semantic search or similarity matching to your server (VectoriaDB)
• Integrating an external npm package as a FrontMCP provider
• Building tools that wrap third-party services (databases, APIs, ML models)

Recommended

• Looking for patterns to structure external service integrations
• Deciding between provider-based vs direct integration for a library
• Adding capabilities like applescript automation, VM execution, or data processing

Skip When

• You need to build core MCP components (see frontmcp-development)
• You need to configure auth, transport, or CORS (see frontmcp-config)
• You need to write a plugin with hooks and context extensions (see create-plugin)

Decision: Use this skill when integrating external libraries into your FrontMCP server as providers or tools.

Prerequisites

• A FrontMCP project (see frontmcp-setup if you don't have one).
• The external library installed as a runtime dependency (not devDependency).
• Familiarity with FrontMCP providers and tools (see create-provider, create-tool).

Steps

1. Pick the integration shape — provider for stateful clients (DB, search index), tool-only for stateless one-shot calls.
2. Wrap the library in a provider — declare a typed DI token and a @Provider class so consumers depend on the boundary, not the library.
3. Register it — add to @App({ providers: [...] }) or @FrontMcp({ providers: [...] }).
4. Expose via tools/resources — call this.get(TOKEN) in ToolContext/ResourceContext; never import the library directly from the tool.
5. Handle errors at the boundary — translate library-specific errors into PublicMcpError/InvalidInputError so MCP clients see structured failures.