--- title: AX, DX, ADX: naming the three audiences your API now has to serve slug: ax-dx-adx-naming-the-three-audiences-your-api-now-has-to-serve published_at: 2026-03-03 15:43:00 +0000 updated_at: 2026-03-03 20:46:00 +0000 summary: In this Article, you will learn how to serve three API audiences: DX for devs, ADX for AI coding agents, and AX for end-user agents, plus the tooling to nail each. 🚀 tags: [] author: CJ Avilla url: https://www.cjav.dev/articles/ax-dx-adx-naming-the-three-audiences-your-api-now-has-to-serve type: article --- # AX, DX, ADX: naming the three audiences your API now has to serve *Published: March 03, 2026* The acronyms are proliferating faster than their definitions. Over the past 18 months, I've seen "AX" making the rounds on X and LinkedIn, often used interchangeably with "DX" or as a vague gesture toward "AI stuff." Here is my mental taxonomy that cuts the confusion. ## DX: developer experience (the original) Developer experience (DX) is the oldest and most established of the three terms. It describes how easy it is for a human developer to understand, integrate, and ship with your API. Good DX shows up in: - SDKs in every language your users actually work in - Reference docs that load fast and stay accurate - Runnable code examples that work out of the box - Migration guides, onboarding tutorials, and sandbox environments - The quality of error messages when something goes wrong DX is what your developer relations and developer enablement teams have always worked on. It has not changed. What has changed is that DX is now one of three distinct things your platform has to get right, not the only one. ![DX vs AX vs ADX](/rails/active_storage/blobs/eyJfcmFpbHMiOnsiZGF0YSI6NDkyOSwicHVyIjoiYmxvYl9pZCJ9fQ==--e2e90b94abadc72fa69f47c2099a4b8148f48ee1/Generated Image March 03, 2026 - 3_31PM.png) ## AX: agent experience Agent experience (AX) describes how well an AI agent can access and use your API on behalf of an end user. The canonical AX scenario: a user opens a chat interface and types "find the document that Bill most recently approved in Box." An AI agent receives that intent, reasons about which API endpoints to call, executes them, and surfaces the result. The user never writes code. The user may not even know an API is involved. [SDK code mode MCP servers](https://www.stainless.com/blog/sdk-code-mode) are great at this btw. The task for AX, at least for me at Stainless, is to make sure that agents can reliably understand what a customer's API offers, select the right operations, and call them correctly at runtime on behalf of end users. The infrastructure that supports AX is primarily your MCP server, specifically the tools oriented toward execution. ## ADX: agentic developer experience Agentic developer experience (ADX) describes how well an AI agent can help a developer build an integration with your API. The user here is still a developer. The difference from classic DX is that the developer now has an AI assistant doing much of the work. The canonical ADX scenario: a developer opens Cursor and types "build an integration with Box using the Python SDK so that I can auto-approve documents from our customer portal." An AI coding agent might use the MCP server's `search_docs` tool to read documentation, writes the integration code, runs into a type error, and iterates. Whether that agent succeeds depends almost entirely on the quality of what you have published: your SDK, your docs, and how well your content is structured for a model to retrieve and reason about. The agent is a capability devs are using. My job for ADX at Stainless is to make the tools and skills available to the agent as effective and accurate as possible. The infrastructure that supports ADX spans three surfaces: - SDKs: typed, idiomatic, with accurate docstrings the model can surface as inline hints - Docs: structured, accurate reference content the model can retrieve and cite - MCP server (search mode): a `search_docs` tool the agent can query when it needs to look something up mid-task ## The same MCP server, two different orientations One thing that can confuse teams: both AX and ADX involve an MCP server. The distinction is in how that server is used and what it needs to be optimized for. | | AX (agent experience) | ADX (agentic developer experience) | |---|---|---| | Who is using the agent? | An end user | A developer | | What is the agent trying to do? | Access data or trigger actions | Write integration code | | MCP orientation | Execute: run operations on the user's behalf | Search: retrieve context to generate code | | Latency sensitivity | High (user is waiting) | Moderate (developer can tolerate a pause) | | Error tolerance | Low (end users expect reliability) | Higher (developers can debug and retry) | | Primary Stainless surfaces | MCP tools (execution) | SDK + Docs + MCP tools (search) | The same underlying MCP server can support both modes. ## Why I think the distinction matters Consider three distinct audiences with overlapping but non-identical needs: - Human developers (DX): need SDKs, docs, and enablement content they can read and reason about themselves - Agents acting on behalf of developers (ADX): need structured, machine-readable content and search-oriented MCP tools - Agents acting on behalf of end users (AX): need execution-oriented MCP tools with rich schema and description Your platform now needs to serve all three. ## What Stainless builds for each Stainless generates the SDK and MCP infrastructure that sits at the intersection of all three surfaces. - For DX: idiomatic, typed SDKs in [Python](http://stainless.com/docs/targets/python), [TypeScript](http://stainless.com/docs/targets/typescript), [Go](http://stainless.com/docs/targets/go), [Java](http://stainless.com/docs/targets/java), and more, generated from your OpenAPI spec and kept in sync with every API change. Accurate method signatures, generated examples, and changelog tooling that keeps documentation honest. - For ADX: those same SDKs carry type information AI coding agents use for inline hints and retrieval. [Docs](https://www.stainless.com/products/docs) generated from the same source-of-truth. MCP servers with search-oriented tools that let coding agents look up your API surface mid-task. - For AX: MCP servers with execution-oriented tools, generated from the same OpenAPI spec, with description quality and schema precision tuned for model selection at runtime. The underlying bet is that your OpenAPI specification is the single source of truth for all three. Generate well from it, and your platform serves human developers, AI coding agents, and end-user agents consistently. ## A note on where I think this is heading These three categories will stay distinct even as the tooling around them evolves. Human developers are not going away. AI coding agents are getting better at using SDKs and docs that were written for humans. End-user agents are becoming a primary interface for many categories of software. The terminology is still settling. "AX" is the term we see most in the ecosystem. "ADX" is newer and less established. What matters more than the labels is the underlying distinction: who the agent is acting on behalf of, and what they need to succeed. Platform teams that get this right early will have a compounding advantage. The same investment in spec quality, SDK accuracy, and MCP quality pays off across all three audiences simultaneously. [Stainless](https://stainless.com) helps API platform teams generate SDKs, docs, and MCP servers from their OpenAPI spec. If you are thinking through your AX, DX, or ADX strategy, the docs are a good starting point. --- [Back to all articles](https://www.cjav.dev/articles) --- ## Hey Agent, thanks for visiting! 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