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Build Agent

AnthropicOfficialPublished by Anthropic

  • Skill
  • Meta (authoring, orchestration, planning, memory)
  • Agent tooling
  • Apache-2.0
  • No issues found
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From the author

Turns a task the owner keeps doing by hand into a named, reusable skill they can trigger by name or put on a schedule. Watches them do it once or listens to them describe it, works out what varies and what stays fixed, writes the skill with approval checkpoints in the right places, registers it with the router, and shares it with the team. This is how a business gets a workflow nobody shipped for them. Use this whenever the owner describes something repetitive they wish were automatic — including phrasings like "I do this every week," "can you remember how to do this," "make this a thing I can just ask for," "build me an agent," "automate this for me," "turn this into a workflow," or "I want this to happen every Monday." Reach for it when they describe a routine, even without asking for automation.
— the description by Anthropic

AutoGineer summary

Written by AutoGineer from the skill’s own files, not by the author

Build Agent is a meta-skill designed to capture and formalize an owner's manual workflows into structured, executable agent skills. It guides the process of observing a task, identifying variable versus fixed components, implementing necessary approval gates for safety, and registering the resulting skill for future use or scheduling. By focusing on the owner's specific terminology and validating results against known outcomes, it ensures the generated automation is both trustworthy and practical for team-wide adoption.

What it does

  • Observes and extracts task specifications from live conversations or detailed descriptions.
  • Distinguishes between fixed process steps and variable inputs like dates or amounts.
  • Identifies and inserts approval gates for consequential or ambiguous actions.
  • Generates standardized skill documentation including frontmatter and procedural steps.
  • Validates the new skill against known-good results before deployment.
  • Registers the skill for manual triggering or automated scheduling.

When to use it

  • When an owner describes a repetitive task they perform manually.
  • When a user asks to automate a routine or build a custom agent.
  • When a user expresses a desire for a task to occur on a recurring schedule.
  • When you need to convert a one-off manual process into a reliable, reusable workflow.

Advantages

  • Reduces manual effort by automating recurring business routines.
  • Ensures safety through mandatory approval gates for sensitive actions.
  • Maintains user trust by using the owner's specific terminology.
  • Enables team-wide collaboration by sharing formalized, tested skills.
  • Prevents over-automation by balancing manual oversight with execution.

Usage examples

“I do this every Monday, can you build me an agent to handle my commission reconciliation?”
The agent will analyze your current process, identify the fixed steps and judgment points, and draft a reusable skill for commission reconciliation.
“I want this to happen every week without me, can you turn this into a workflow?”
The agent will capture the steps of your current task, build a formal skill, and set up a recurring schedule for it to run automatically.

Install

  1. Download the skill as a ZIP:

    https://mp-staging.autogineer.com/agent-skills/anthropics/build-agent/download

  2. Unzip it into the cross-client skills folder of your project:

    mkdir -p .agents/skills && unzip build-agent.zip -d .agents/skills

Documentation by Anthropic

Build Agent

Turn something the owner does every week into something they ask for by name.

This is what keeps the plugin from having to ship every industry's workflow. No catalog can cover a septic contractor's permit routine or an insurance agency's carrier commission reconciliation. Those owners can build them.

Step 1 — Watch it happen, or hear it described

Two starting points, and the first is much better.

Best: they just did it in this conversation. If the owner has walked through the task with you — pulled the files, made the decisions, corrected you twice — that transcript is the specification. Extract it rather than re-interviewing them. The corrections they made are the most valuable part, because they encode judgment the owner would never have thought to state.

Otherwise: they describe it. Ask them to walk through the last time they did it, concretely. Real specifics beat an abstract description every time — "last Tuesday I pulled the carrier file, matched it against what we'd booked, and chased six discrepancies" tells you more than "I reconcile commissions."

Read reference/capture.md for how to get a complete picture without an interrogation.

Step 2 — Separate what varies from what stays fixed

This is the whole craft of the step. A skill that hardcodes last Tuesday's specifics only works on last Tuesday.

For each part of the task, decide:

  • Fixed — the sequence, the sources, the output format, the rules

  • Varies — dates, names, amounts, which file, which customer

  • Judgment — the parts where the owner decides, which become approval gates

The corrections the owner made while walking through it usually mark the judgment points. When someone says "no, not that one — we skip anything under USD 50," that is a rule. When they say "hmm, depends," that is an approval gate.

Step 3 — Find the approval gates

Every step that sends, spends, publishes, or deletes needs a gate. So does every step where the owner hesitated.

Do not gate everything — a skill that asks permission nine times is worse than doing it by hand. Gate the consequential and the ambiguous, and let the rest run.

Read reference/skill_authoring.md for where gates belong and how to phrase them.

Step 4 — Write it

Produce a real skill in the same shape as everything else in this plugin: a SKILL.md with frontmatter and numbered steps, plus a reference/ folder if the detail warrants it.

Requirements it must meet, same as every shipped skill:

  • Name and folder match, lowercase with hyphens

  • Description says what it does and when to trigger, in third person

  • A real fallback for when a connector is missing

  • Approval gates on anything consequential

  • Never invents a number; missing data is reported as missing

Write it in the owner's terms, not in generic business language. If they call it "the carrier file," the skill says carrier file. A skill full of unfamiliar vocabulary is one they will not trust to run unattended.

Step 5 — Test it on a real case, before they rely on it

Run the new skill against a case the owner already knows the answer to — ideally the exact one they walked through. Show the output next to what they got by hand.

This is the step that determines whether the skill gets used. An owner who has seen it reproduce a known-good result will schedule it. One who hasn't will run it manually and check it every time, which saves nothing.

If it doesn't match, fix the skill and run it again. Do not ask the owner to accept a near-miss.

Step 6 — Register and set the cadence

Add it to smb-router so plain-English requests reach it, and record the trigger phrases the owner actually uses.

If it is a recurring task, offer to schedule it. Scheduling is what converts "a skill I could run" into "something that happens without me," which is the outcome they wanted.

Step 7 — Share it, with approval

Offer to share with the team. Say what sharing means: who gets it, what data it can reach, and what it can do unattended.

Be specific about the risk when a skill sends, spends, or writes. A skill that emails customers, running for someone who did not build it and does not know its assumptions, is a real hazard. Recommend draft-only for shared skills that send anything.

What not to do

  • Do not re-interview about a task they just walked through. The transcript is the spec.

  • Do not hardcode the example. Names, dates, and amounts vary; the sequence does not.

  • Do not gate every step. Nine approvals is worse than doing it by hand.

  • Do not skip the test run. An untested skill gets checked manually forever, which saves nothing.

  • Do not write it in generic business language. Their words, or they won't trust it.

  • Do not build something that sends or spends without approval gates. Ever, regardless of what the owner asks for.

After the build

The owner now has a named skill they can trigger or schedule. If the new skill hit a tool that isn't connected, "connect to my ERP" (build-connector) is the natural next step — it turns the missing system into a working source. Also nearby: "brief me" to fold the new output into the daily picture, and "Monday brief" if the skill should feed the weekly one. Offer at most three, and skip any offer the owner already declined this session.

Reference files

  • reference/capture.md — getting a complete picture of the task without an interrogation

  • reference/skill_authoring.md — the structure, frontmatter, and where approval gates belong

  • reference/gotchas.md — the failure modes that produce a skill nobody uses

Files

reference/capture.md

Capturing the Task

The goal is a complete picture without an interrogation. Owners abandon this halfway through if it feels like filling in a form.

Best case: they just did it

If the task was walked through in this conversation, the transcript is the specification. Do not start over with questions.

Extract:

  • The sequence — what happened, in order

  • The sources — every file, system, or place data came from

  • The decisions — every point where a judgment was made

  • The corrections — everywhere the owner said "no, actually"

The corrections are the most valuable part. They encode rules the owner would never have thought to state, because to them it is obvious. "No, skip anything under USD 50" is a business rule that would not have surfaced in any interview.

Then confirm the shape in one pass rather than many:

Here's what I think this is:

  1. Pull the carrier commission file from the monthly email
  2. Match each line against what's booked in the CRM
  3. Flag anything off by more than USD 5
  4. Draft a chase email per discrepancy, one per carrier
  5. You review and send

Rules I picked up: skip anything under USD 50. Anything over USD 500 you want to
look at yourself before it's chased.

Right?

One block, one question.

Otherwise: ask about the last time

An abstract description produces an abstract skill. Anchor to a specific instance:

Walk me through the last time you did this. What did you open first?

Then follow the actual sequence. Ask what happened next, not what usually happens.

The questions that produce the most useful answers:

  • What did you open first?

  • Where did that number come from?

  • What would make you stop and think here?

  • What went wrong the last time this went badly?

  • What would you never want this to do on its own?

The last two matter most. The failure mode and the hard limit are what turn a fragile automation into one the owner will let run unattended.

What to capture, checklist

Task:        <what the owner calls it>
Trigger:     <what makes them do it — a date, an email, a request>
Frequency:   <weekly, monthly, ad hoc>
Sources:     <every system, file, or inbox involved>
Sequence:    <steps, in order>
Rules:       <thresholds, exclusions, exceptions>
Judgment:    <where they decide, not the process>
Output:      <what exists at the end, and who sees it>
Never:       <what it must not do on its own>
Time:        <how long it takes by hand — this is the ROI number>

The Time line is worth asking for explicitly. "Two hours every Monday" is what the owner will repeat when someone asks whether this was worth it — that number is worth keeping.

How much to ask

Three to five questions, maximum, before showing a draft.

An owner who wanted to save two hours a week will not spend forty minutes specifying a skill. Get to a draft fast — a wrong draft is easier to correct than a blank page, and the correction produces better information than the question would have.

That's enough to build a first version. Let me draft it and you tell me what's
wrong — faster than me guessing at more questions.

When the task is too big

Some described tasks are really four tasks. "Manage my whole month-end" is not one skill.

Say so, and propose the split:

That's really three things: reconciling the accounts, chasing the gaps, and
writing the summary. Building it as one skill means it breaks in ways that are
hard to find.

Want to start with the reconciliation? It's the part that takes longest, and
the other two get easier once it exists.

Start with the piece that takes the most time by hand. Momentum matters more than completeness here — an owner with one working skill builds three more.

When the task shouldn't be a skill

Sometimes the honest answer is that a shipped skill already covers it, or that the task varies too much to automate.

Say so plainly:

This is close to what `invoice-chase` already does. Want me to look at whether
it covers your case before we build something new?

Or:

Every one of these seems to go differently. I could build something that
handles the common shape, but you'd still review each one — which is most of
the work. Worth it, or would a checklist serve you better?

Building an unnecessary skill costs the owner trust when it fails, and it clutters the router for every future request.

Requirements and compatibility

Written for: Claude Code, Claude apps

Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta

“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.

Needs: Declares allowed tools

Security

No issues found by our static scan· No issues found

A static scan is not a guarantee. Skills are third-party content: review a skill before you let an agent use it.

Attribution and licence

Published by
Anthropic
Publisher
Anthropic (Official)
Source
anthropics/knowledge-work-plugins · small-business/skills/build-agent · commit e050c2e
Licence
Apache License 2.0 (redistribution allowed)
  • LICENSE (added by AutoGineer from LICENSE)
  • ATTRIBUTION.md (written by AutoGineer)
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Download ZIP

The ZIP holds the skill’s files, its licence files and an ATTRIBUTION.md. Download build-agent.zip