Stainless vs Speakeasy for MCP in 2026: After Stainless Joined Anthropic

If you are starting a new MCP server today, Stainless is not an option. On 18 May 2026, Stainless announced it was joining Anthropic and said new signups, projects and SDKs "will not be available." For new projects, the realistic choice is Speakeasy or another OpenAPI-to-MCP generator.

If you already have a Stainless-generated MCP server, the question is different: keep the code you own and maintain it yourself, or move to a vendor that will keep generating it. This page covers both readers.

Checked against: Stainless's announcement, Stainless MCP docs and Speakeasy MCP generation docs on 28 October 2026. eSEOspace did not test either product.

At a glance

What happened to Stainless

Stainless's founder wrote that "Stainless is joining Anthropic" in a post dated 18 May 2026. The post says: "we'll be winding down all hosted Stainless products, including our SDK generator. Starting today, new signups, projects, and SDKs will not be available."

It also says: "As always, you own the SDKs you've generated to date, and have full rights to modify and extend them however you wish." Customers are pointed to app.stainless.com/transition for help moving to other options. When we tried that address on 28 October 2026, it returned an error, so contact Stainless directly if you cannot reach it.

The post gives no shutdown date and does not mention MCP servers by name. Stainless's MCP docs and pricing page were still live with no notice when we checked. Treat the announcement as the current word.

If you already have a Stainless MCP server

Stainless's docs describe what you have. The MCP server is "a subpackage of your TypeScript SDK" at packages/mcp-server. It exposes "a code execution tool and a docs search tool." It publishes to npm with your SDK's version and can ship as a Docker image or an MCPB file.

Check three dependencies before you decide to keep it:

• Docs search. The docs search tool calls the Stainless API, which "serves the documentation in Markdown format." If that API goes away, the tool may stop working. Test it.
• Hosted code sandbox. The docs already mark stainless-sandbox mode as deprecated and say a 410 Gone response means you should "run the server with --code-execution-mode=local instead." Local mode needs Deno.
• Stainless hosting. The remote deployment docs say "Stainless-hosted MCP servers are deprecated" and recommend self-hosting the Docker image.

If your server runs locally or in your own Docker setup, it can keep working as code you own. But nobody will regenerate it when your API or the MCP spec changes. Our page on the 2026-07-28 spec changes shows how much a spec release can move.

Where Speakeasy is stronger

For new projects, Speakeasy's main advantage is simple: you can buy it. It also has real product strengths.

Two ways to run. Its generation docs describe speakeasy quickstart --mcp, which creates "a TypeScript-based MCP server" you deploy yourself. Its hosted MCP server page says Speakeasy "generates, hosts, and secures your MCP server."

Reviewable tools. The hosted page says "every API operation becomes a tool, regenerated on each push from CI." Scopes such as --scope read can mount a read-only server. For large APIs, a dynamic mode exposes four meta-tools instead of every tool.

Spec changes handled. Speakeasy says revisions "such as the move to stateless MCP are handled on the platform, not in your codebase."

Auth and logs. Hosted servers can use your identity provider or Speakeasy as the authorization server. Speakeasy says "every call is logged with the customer, tool, client, and result."

Speakeasy also publishes a customer story. It says PlanetScale's hosted server grew from about 4,700 tool calls in its first month to 206,000 in its fifth. That is Speakeasy's figure. Our Speakeasy spotlight covers its gateway product too.

Where Stainless's design was stronger

This matters if you are deciding whether to keep a Stainless server.

Small context footprint. Two tools take little room in the model's context window. Stainless said this design is "more accurate and token-efficient than architectures that expose one tool per API method." Its MCP product page claims "3x fewer tool calls," without showing its method.

A tight local sandbox. In local mode, model-written code runs in a Deno subprocess that "cannot write to the filesystem, start subprocesses, or reach any other host" beyond your API.

If you move to Speakeasy, expect a different shape: many named tools, or Speakeasy's code mode, instead of one code tool. Prompts and agent tests built around the old tools may need rework. Our guide to MCP tool design explains the trade-off.

Pricing

Stainless. Not available to new customers, per the announcement. The pricing page still shows plans, but the post says new signups "will not be available."

Speakeasy. The pricing page lists pay as you go with no platform fee: $0.35 per million tokens of session storage, $0.99 per million tokens scanned for risk and $20 per GiB of MCP gateway egress. Enterprise is an annual contract. The page does not list a separate price for generating or hosting an MCP server, and the hosted page says "Deploy for free." Ask Speakeasy for a quote before you migrate.

Security and admin controls

Stainless permissions. The permissions docs offer allow and block lists for the code tool. They warn: "Determined users can bypass these checks through code obfuscation." If you keep a Stainless server, rely on restricted API tokens, as the docs advise.

Unmaintained code risk. A server no vendor updates still needs security patches, dependency updates and spec changes. Assign an owner in your team.

Speakeasy controls. Scopes, named tools and the x-speakeasy-mcp extension control which tools mount. Its security page says audits confirm "SOC 2 Type 2 and ISO 27001 certification."

For checks that apply to any server, see our MCP security hub.

Which to choose

Keep your Stainless-generated server if:

• It runs locally or in your own Docker setup, not on Stainless hosting.
• Your API changes rarely and you can assign a maintainer.
• Its docs search tool still works, or you can replace it.

Pick Speakeasy if:

• You are starting a new MCP server from an OpenAPI document.
• You are a Stainless customer who wants a vendor to keep generating your server.
• You want hosting, OAuth and per-customer logs handled for you.

Look at other generators if:

• You want a different tool design or pricing model. See our APIMatic spotlight and Fern spotlight, and the full set of MCP comparisons.

Next step

A migration is a good time to redesign. Decide which operations agents should see, then compare a generated server with a hand-built one. Our MCP development team can help you plan either path.

Frequently asked questions