Agents read your API errors. Put the fix in them.

A bare 400 leaves an agent guessing, and its wrong guesses come back as support tickets. Restless adds the fix to the error response, so the next agent corrects the call and finishes the job. No redeploy.

Free plan, no card. Set it up with one prompt to your coding agent.

/v1/shipments

POST /v1/shipments {"weight": "2.5kg"}

400 {"error": "invalid_request"}

POST /v1/shipments {"weight": "2.5kg"}

400 {"error": "invalid_request"}

POST /v1/shipments {"weight": "2.5kg"}

400 {"error": "invalid_request", "fix": "Send weight in grams as an integer. Example: 2500"}

POST /v1/shipments {"weight": 2500}

201 Created

What is Restless

Restless manages everything between your API and the agents that call it, from the docs they read to the fix when a call fails.

Built for small teams with a public API on Node, Python, Ruby or Go. It works alongside the docs you already have on ReadMe, Mintlify, Fern or GitBook.

Built by ReadMe
12 years in API docs
Docs for tens of thousands of APIs
72% of traffic to ReadMe-hosted docs now comes from agents

An agent gets a 400. It guesses. Then it guesses again.

An agent calls an endpoint that doesn't exist, or sends a field your API rejects. It gets back a bare error with nothing to act on, so it guesses, retries or gives up. You can't see what it was trying to do.

/v1/shipmentsretry ×3

14:02:07.112 POST /v1/shipments 400 {"error": "invalid_request"}

14:02:08.940 POST /v1/shipments 400 {"error": "invalid_request"}

14:02:11.385 POST /v1/shipments 400 {"error": "invalid_request"}

Your error messages were written for a developer reading logs later. An agent reads them the moment the call fails, and acts on whatever they say.

"users complaining our api is down because the chatbot hallucinated the endpoint"

API owner on Hacker News

Every wrong guess becomes a ticket.

The ticket says your API is down. Most agents start each session fresh, so the next one makes the same bad call. The person who asked the agent for help leaves with nothing done, and you never hear why.

One API owner found 107 of 121 agent tool chains broken for months before anyone noticed.

Your tools help agents read, or tell you something broke. None of them answer the agent.

What you have	What it does	Where it stops
llms.txt and Markdown docs	Helps agents read your docs	The call still fails
A hosted MCP server	Gives agents your endpoints as tools	Returns the same bare error
Your error tracker	Records the 400 for your team	Tells the agent nothing
Better error text in code	Fixes one message	Every change waits on a deploy

Restless works alongside ReadMe, Mintlify, Fern and GitBook. Keep your docs where they are.

Agent recovery

Your API errors tell agents how to fix the call.

/v1/shipments

POST /v1/shipments {"weight": "2.5kg"}

400 {"error": "invalid_request"}

POST /v1/shipments {"weight": "2.5kg"}

400 {"error": "invalid_request"}

POST /v1/shipments {"weight": "2.5kg"}

400 {"error": "invalid_request",

"fix": "Send weight in grams as an integer. Example: 2500"}

POST /v1/shipments {"weight": 2500}

201 Created

See the failed calls. Every request lands in Restless, so you can see which calls fail and where callers give up.
Write the fix once. Plain language, with no code change and no redeploy.
Every agent gets it. Restless adds your fix to the error response for every matching call. The agent corrects the request and retries.

Nothing reaches an agent until you approve it.

The task finishes, so nobody writes in to say your API is down.

Also on the free plan

Every call in one place. See which endpoints get hit, which fail, and where callers get stuck.
Agent feedback. Agents flag missing endpoints and confusing docs to an inbox that syncs to Linear.
Agent-ready docs. Restless builds agent-readable docs and a hosted MCP server from your OpenAPI spec.

Set it up with one prompt.

1
Sign up with GitHub or Google. No card.
2

Paste the setup prompt into your coding agent. It works in Claude Code, Cursor, Codex and VS Code. Prefer to do it yourself? Install the SDK for Node, Python, Ruby or Go.

Set up Restless in this repo
3
Watch the first calls arrive. Then write your first fix.

Free plan, no card. Set it up with one prompt to your coding agent.

Questions your head of engineering will ask

Will it slow down my API?

No. The SDK sends logs in the background, and fix lookups happen in-process, with no network call in the request path.

What happens if Restless goes down?

Your API keeps serving traffic, because the SDK fails open. And we never drop your traffic for billing reasons.

What happens to personal data?

The SDK strips personal data before anything leaves your server, and the SDK is open source. Logs are kept for 30 days.

Who decides what agents are told?

You do. Nothing reaches an agent until you approve it.

Free to start, with every feature.

Free plan

1,000 credits every month, enough for about 1M API requests
Every feature included
No card
Pay only if your traffic outgrows the free credits. $100 buys 1,000 more.

Free plan, no card. Set it up with one prompt to your coding agent.

The first 100 teams get a Slack channel with the Restless team, plus an optional setup call.

Find out what agents do with your API. Finish this at your desk.

If agents already handle your API fine, the free plan will show you that too. If they don't, you'll see the failed calls as soon as traffic arrives, and you can fix the first one the same day.

Setup needs the computer where your API code lives. We'll email you the prompt, so you can paste it into your coding agent there.

Free plan, no card. The first 100 teams get a Slack channel with the Restless team.

/v1/shipments

POST /v1/shipments {"weight": 2500}

201 Created