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Build Agent

AnthropicOfficialPublished by Anthropic

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

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/gotchas.md

Gotchas

Failure modes that produce a skill nobody uses, or one that does damage unattended.


Gotcha: re-interviewing about a task they just walked through

Why it matters: The owner spent twenty minutes doing the task with you. Opening with "so tell me about your process" says none of it was being paid attention to.

Bad
Owner: "That was great — can you remember how to do that?"
Claude: "Sure! Let's start by understanding your workflow. What systems do
        you use for commission data?"
Good
Claude: "Here's what I think this is: [the sequence, the rules picked up from
        the corrections]. Right?"

The transcript is the specification. The corrections are the business rules.


Gotcha: hardcoding the example

Why it matters: A skill built around last Tuesday works exactly once. The owner runs it next month, gets nonsense, and never opens it again.

Bad
Pull the Continental commission file for June and match against the
34 policies booked.
Good
Pull the current month's carrier commission file from the statement email.
Match every line against policies booked in the CRM for that period.

Fixed: the sequence, the sources, the rules. Varies: the month, the carrier, the counts.


Gotcha: gating every step

Why it matters: A skill that asks nine times is slower than doing the task manually. The owner stops running it and cannot articulate why.

Bad

Approval before pulling the file, before matching, before flagging, before drafting, before each email.

Good

Gate the sends and the ambiguous judgment calls. Let reading, matching, computing, and drafting run:

6 chase emails, one per carrier, USD 2,340 in discrepancies, from your address.
Send them?

One gate, at the consequential moment.


Gotcha: a vague gate

Why it matters: "Ready to proceed?" asks the owner to approve something invisible. The first time it goes wrong, every gate in the plugin loses credibility.

Bad
I've prepared the emails. Ready to proceed?
Good

State the count, the recipients, the amounts, and the account it sends from. Consent needs to be informed to be worth anything.


Gotcha: skipping the test run

Why it matters: An owner who hasn't seen the skill reproduce a known-good answer will check its output manually every time. That saves nothing, and eventually they stop running it.

Bad

Build it, register it, tell them it's ready.

Good

Run it against the case they walked through, and show both:

Ran it on June's file — the one you just did by hand.

Found the same 6 discrepancies, same amounts. It also flagged a 7th at USD 61
on the Meridian file that you skipped. Was that deliberate, or worth adding
to the rules?

That last question is how the skill gets a rule it was missing.


Gotcha: generic business language

Why it matters: A skill written in vocabulary the owner doesn't use feels like it belongs to someone else. They won't trust it to run unattended, which was the whole point.

Bad
Reconcile revenue recognition variances against booked commitments.
Good
Match the carrier file against what's booked and flag anything off by more
than USD 5.

Gotcha: a shared skill that sends

Why it matters: A skill that emails customers, run by someone who didn't build it and doesn't know its assumptions, is a genuine hazard. The owner sharing it is not thinking about that.

Bad
Shared with your team.
Good
Sharing this with Teri and Marcus. Worth knowing: it sends email from
whoever runs it, and it assumes the USD 50 skip rule you set.

Recommend I set it to draft-only for them — they'd review and send rather
than it going out automatically. Your call.

Gotcha: building a skill that already exists

Why it matters: A duplicate clutters the router, competes for triggers with the shipped skill, and will be maintained by nobody.

Bad

Build "chase unpaid invoices" from scratch.

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

Gotcha: one skill that's really four

Why it matters: A skill covering an entire month-end process breaks in ways that are hard to isolate, and a skill the owner can't debug is one they abandon.

Bad

Accept "automate my month-end" as a single skill.

Good

Name the split and start with the heaviest piece:

That's three things: reconciling, chasing the gaps, and writing the summary.
Want to start with the reconciliation? It's the part that takes longest, and
the others get easier once it exists.

Gotcha: no fallback

Why it matters: A skill that requires a connector the owner might lose access to is a skill that breaks silently. This audience changes tools constantly.

Bad

The skill assumes the carrier portal connector exists.

Good
No connector for your carrier portal. Forward me the monthly statement and
I'll do the rest — same output, one extra step.

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)
Synced

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Download ZIP

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