Plugins, APIs and integrations: how to make your business discoverable to assistant ecosystems

Short answer: to make your business discoverable to AI assistants, give them safe, well-described ways to use your data and actions. That usually means an API with a clean OpenAPI spec, then a lightweight plugin or integration so Copilot, ChatGPT/GPTs and Gemini can find and invoke it. Where available, adopt the Model Context Protocol (MCP) so multiple assistants can reach the same capabilities with less custom work. (learn.microsoft.com)

Which assistant ecosystems should I design for first?

If you sell to knowledge workers, prioritise Microsoft Copilot and Google Gemini in Workspace—they’re becoming default in enterprise stacks and support governed, admin‑controlled integrations. Copilot surfaces plugins that wrap REST APIs (via OpenAPI) or MCP servers; admins approve availability and usage. Gemini supports third‑party integrations in Gmail, Docs, Drive and more, with admin controls for who can connect them. (learn.microsoft.com)

For public reach and developer overlap, plan for ChatGPT. You can expose actions to your API inside custom GPTs and, where applicable, migrate to ChatGPT plugins as OpenAI consolidates routes for external actions.

What’s the minimum I need to be “callable” by assistants?

• A stable HTTPS API that does one useful thing end‑to‑end (e.g., “get price and availability”, “create support ticket”).
• An OpenAPI description with concise operation summaries and parameters; assistants use these descriptions to decide when to call you. For Copilot, this directly improves selection. (learn.microsoft.com)
• Clear auth: API key for server‑to‑server, OAuth when you need the user’s account.
• Response semantics: return machine‑readable fields (ids, timestamps, URLs) and, if you want rich UI in Copilot, Adaptive Card templates or MCP app views. (learn.microsoft.com)

If you can, expose an MCP server as a façade over your domain. MCP is an open standard many hosts (including Claude tools and IDEs) speak; it reduces one‑off integrations. Recent spec updates formalise discovery, stateless requests and extensions, which helps large organisations govern at scale.

When should I build a simple plugin vs just expose an API?

Use this practical rule:

• Start with a public API + OpenAPI. It creates the surface assistants need and keeps you platform‑agnostic. (learn.microsoft.com)
• Add a lightweight plugin when a channel can materially boost conversion or usability (e.g., Copilot plugin to be chosen in Teams/Word/Excel; ChatGPT plugin for power users). Plugins package your API and prompts so the orchestrator can discover and call you reliably. (learn.microsoft.com)
• Prefer MCP if you need one integration to reach multiple hosts, or you want dynamic tool discovery without republishing. Copilot supports dynamic tool resolution for MCP‑based plugins. (learn.microsoft.com)
• For Google Workspace, publish an integration users can connect in Gemini across Gmail/Docs/Drive—especially valuable if your product lives in email, tasks or docs workflows and you need admin‑approved rollout.

Examples

• B2B SaaS helpdesk: expose “create_ticket”, “get_ticket_status” as API; ship a Copilot plugin so account managers can act in Teams; optionally add MCP for IDE/agent use. (learn.microsoft.com)
• Ecommerce inventory: API first; ChatGPT action for quick Q&A; Gemini integration for marketing teams working in Sheets and Gmail.

How do assistants actually “choose” my integration?

Under the hood, orchestrators match user intent to tool descriptions. In Copilot, the plugin description and your OpenAPI summaries strongly influence selection; when agents have more than five plugins, semantic matching based on plugin descriptions decides what’s injected, so clarity matters. In ChatGPT/GPTs, action schemas and auth determine whether the model can call your endpoint. In Workspace, admins gate what’s even connectable. (learn.microsoft.com)

Checklist to be choosable:

• Write one‑line, verb‑first summaries per operation (e.g., “Get live room rate by hotel_id and date”).
• Keep required params minimal and typed; make optional params truly optional.
• Return explicit errors with actionable messages.
• Add examples for the common happy path in your OpenAPI.
• Name your plugin and operations in business language end‑users use.

What about security and governance?

• User consent prompts: Copilot asks before sharing data with a plugin the first time; actions that modify data may require confirmation. Plan UX around that. (learn.microsoft.com)
• Admin control: Microsoft 365 and Google Workspace both let admins approve which plugins/integrations are available and who can use them. Expect audits.
• Auth patterns: Use OAuth when you’re acting on a user’s account; API keys for backend “service” actions. Segment scopes and rotate keys.

Risk/cost matrix for agencies advising clients

Use this to set expectations in proposals.

Low cost / low risk (start here):

• Document an existing API with OpenAPI; add examples and slim responses. Weeks: 1–2. Risk: low (reversible, channel‑agnostic). Impact: unlocks Copilot/API‑plugin route, GPT actions, and future MCP. (learn.microsoft.com)

Medium cost / medium risk:

• Ship a Copilot API plugin for one task, validated with target users in Teams or Word. Weeks: 2–4 including admin rollout. Risk: moderate (governance, selection tuning). Upside: in‑workflow usage. (learn.microsoft.com)
• Publish a Gemini Workspace integration for a specific team workflow (e.g., marketing approvals in Gmail/Docs). Weeks: 3–6 depending on scopes and review. Risk: moderate (admin approvals). Upside: high adoption if you’re a daily tool.

Higher cost / lower platform risk (strategic):

• Build an MCP server over your core domain actions. Weeks: 4–8. Risk: technical investment; platform risk is lower because multiple hosts (Copilot via MCP plugins, Claude tools, IDEs) can use it. Benefits: dynamic discovery, consistent semantics, easier multi‑assistant support thanks to the evolving spec and SDKs. (learn.microsoft.com)

High cost / higher risk (only if there’s clear distribution):

• Full multi‑channel plugin portfolio (ChatGPT + Copilot + Workspace + custom agents) with bespoke UIs. Weeks: 8–16. Risk: ongoing maintenance across policies and runtimes; justify only if there’s proven channel demand.

How do I measure visibility and revenue impact?

Discovery is more than installation—assistants need to recommend and call you. We built Luciqo to track this: it checks what ChatGPT, Claude, Gemini and Perplexity say about your brand, who they recommend instead, which sources they cite, and links that visibility to revenue via Google Analytics, Matomo or HubSpot. Use it to baseline “AI recommendation share” before and after shipping an API or plugin. Luciqo. For a deeper how‑to, see: How to track AI recommendation share and competitors that assistants suggest instead of you and Which sources do ChatGPT, Gemini and Perplexity prefer — and how to get cited by them.

Implementation steps I recommend this week

1. Pick one task to expose (buy, book, create, price). Write the endpoint and OpenAPI. Keep it fast and explicit. (learn.microsoft.com)
2. Wrap it where it matters: a Copilot plugin for your internal users, a GPT action for power users, or a Gemini integration for Workspace teams. (learn.microsoft.com)
3. If you have multiple assistants to serve, put an MCP server in front so you don’t maintain N adapters.
4. Ship, then measure assistant recommendations and citations. Close the loop to pipeline with Luciqo. Luciqo.

If you want a deeper primer on shaping content to be quoted by assistants, start with: GEO Writer checklist: How to write content that AI assistants will quote and Optimising for AI product discovery: what marketers must do for agents to choose your product.

Frequently asked questions

What’s the difference between a plugin and an API?

Your API is the capability surface (endpoints). A plugin is a package that describes how an assistant should call that surface, with auth, scopes and prompts. In Copilot, plugins wrap MCP servers or OpenAPI‑described REST APIs. (learn.microsoft.com)

When should I choose OAuth over API keys?

Use OAuth when actions perform account‑level operations on behalf of a signed‑in user (e.g., send email). Use API keys for server‑to‑server actions without user data.

Is MCP worth it if I only care about one assistant?

If you’re single‑channel today, start with OpenAPI + that channel’s plugin. Add MCP when you need cross‑assistant reach or dynamic tool discovery—Copilot supports MCP‑based plugins. (learn.microsoft.com)

How do admins govern these integrations?

Microsoft 365 and Google Workspace let admins approve or restrict plugins/integrations and audit usage. Expect consent prompts and confirmation for data‑changing actions.

Do GPT actions still work?

Yes. You can configure actions for custom GPTs; OpenAI provides guidance and a migration path where actions consolidate into plugins over time.

How do I make my operations more discoverable to Copilot?

Use verb‑first summaries, minimal required params, accurate types, and examples in OpenAPI; Copilot’s orchestrator relies on these descriptions to choose tools. (learn.microsoft.com)