Keystone AI / Custom AI agents

Custom AI agents that draft the work and wait for your yes.

An AI agent is software with a goal and tools: it reads documents, weighs a judgment call, drafts an output. Keystone builds agents for operating businesses as desks, where a person's approval is a step in the process and nothing leaves without it. Most of a desk is ordinary software. Agents do only the parts that need judgment. That split is what makes them reliable enough to employ.

By David Lai · Updated 2026-09-21 · 6 min read

What

Per-seat desks (agents that draft, a person approves) and engines (standing agent crews Keystone operates, delivering counts on a cadence).

Built with

Claude models inside a deterministic harness: typed outputs, source citations on every draft, a golden-set evaluation before anything goes live.

Never

Agents that send, submit, sign, or act on the world without a person. That is a design choice enforced by the architecture, not a policy.

Cost

Fixed price per desk from a two-week assessment. See what a custom AI agent costs.

What an AI agent is, and the question buyers ask

An agent is AI with a goal and tools. Given a job, it decides which tool to use next, reads what comes back, and keeps going until it has a result. That is different from a workflow, where the steps are written in advance. The agent vs workflow guide covers when each is right.

The question every buyer asks is "so these are AI agents?" The answer: the judgment parts are, yes. The desk is the harness they work inside, and that is what makes them safe to employ.

A desk is where agents report to work

A desk sits under one seat in your company: the estimator, the controller, the vendor coordinator. Five layers, one chassis.

  1. Connections. Read-only, into the systems the seat already uses: email, files, the project platform, the accounting system.
  2. Memory. An answer library that compounds with every job the desk touches. Half the value of the first build; the reason the second desk costs less.
  3. Plays. One per task: collect, extract, assemble, draft, flag. Written once, verified by a person, then trusted the way a machinist trusts a jig.
  4. Gates. Output is always a draft. A desk cannot send, submit, or sign. Enforced by the architecture.
  5. Triggers. Asked, then scheduled, then event-driven, as trust builds.

In production: a vendor onboarding desk that assembles packets from emails and PDFs and tracks insurance certificates, and a work order coordination desk that matches orders to crews and drafts dispatch notes, both at a Chicago-area construction and facilities contractor. Every draft cites its sources and every approval is logged.

Engines: agent crews Keystone operates

A desk responds; an engine runs. When work should arrive as a flow rather than a pile, the agents run in a fixed sequence on their own supply: read the sources, extract, score, rank, deliver. An engine never acts on the world. It writes to your record and hands a person a ranked list. It is Keystone-operated, so nobody on your team supervises it. Examples running today: a signal engine reading public records for funded construction work, and a trend engine scoring demand for a toy maker's design team.

How they are built

Evaluation before anything goes live

Every desk ships with a golden set: real past examples from the seat, graded by the person who sits in it, that the desk must pass before it handles live work and must keep passing when models change. Without evals an agent reaches a demo and never reaches production. With them, the coordinator can see the pass rate and decide how much to trust the queue.

Questions people ask

Can I develop my own AI agent?
For a simple assistant on your own documents, yes, with no-code tools or a model provider's agent features. An agent that reads your business systems, drafts reliable outputs daily, and keeps a person in control needs integrations, a typed harness, evaluation, and an approval gate. That is a software build, and it is what a desk is.
How much does it cost to build a custom AI agent?
Published 2026 ranges run $10,000 to $30,000 for an assistant on your documents and $30,000 to $150,000 for an agent that reads your systems and drafts outputs for approval, plus $500 to $20,000 a month to run. Keystone quotes a fixed price per desk from a two-week assessment. Details in the cost guide.
What are some reputable AI agent consulting companies?
At enterprise scale, the large consultancies and national AI development firms. For an operating business of 20 to 500 people, look for a builder who can show an agent running today in a company like yours, with an approval log and a human override, and whose builders are the ones doing the scoping.

Which seat in your company is buried?

Thirty minutes on where the hours go and which seat gets the first desk. You talk to the people who would build it.

Let’s talk

or write to david@keystoneai.io