Building MCP Servers

An MCP server is a Model Context Protocol endpoint that exposes Celigo Tools and builder-mode APIs as callable tools for external AI agents and MCP clients -- and, optionally, prompt templates, Celigo Storage files, and tools relayed from another MCP server. Concerns when building an MCP server:

• Endpoint identity -- unique relativeURI that, with the account's MCP alias, forms the server's URL
• Tool selection -- which Tool resources to expose, each with an MCP-compatible name
• API selection -- which builder-mode API resources to expose (script-mode APIs are not supported)
• Prompts, files and proxies -- inline prompt templates (prompts[]), Celigo Storage files (resources[]), and an upstream MCP server's capabilities (upstreamMcpConnections[])
• Annotations -- MCP-standard behavior hints (readOnlyHint, destructiveHint, idempotentHint, openWorldHint) that help AI agents decide when and how to call a tool
• Overrides -- per-server connection bindings for a tool's steps. Every tool entry needs one for each step, and they're the only overrides that change what a call does
• Name uniqueness -- tool names must be unique across all tools[] and apis[] entries within the server

MCP servers support configurable authentication of their own -- Celigo OAuth (the recommended choice, which you must turn on explicitly with oauth: {useCeligoOauth: true}), an external IdP, or static API tokens, gated by mcp:read / mcp:write scopes -- plus optional traffic limits and an IP network policy (see Authentication and Scoping). Outbound calls to external systems use the connections referenced by the underlying tools and APIs.

Used alongside tools and APIs. The MCP server is a thin exposure layer -- all processing logic lives in the referenced Tool and API resources.

Composition Patterns