/agent-builder

name: agent-builder
description: >-
  Load immediately after an Agent intent. Then call build-agent with the user's
  request after any required orchestrator-owned prerequisites are ready. Agent
  Builder owns Agent setup and implementation questions. Governs prerequisite
  creation, faithful handoff, targeting, testing, and publishing. Use directly
  for routine Agent follow-ups; rerun intent-recognition only when the requested
  artifact is no longer clear.
recommended_tools:
  - build-agent
  - build-workflow
  - data-tables

Agent Builder

Routing

Use this skill after `intent-recognition` chooses an agent-anchored design, or when the conversation already targets an Agent and the user is continuing that build. Do not rerun intent recognition for routine Agent edits or extensions. Use `build-agent` only for Agent artifacts.

For a new Agent request, make the first `build-agent` call with a faithful copy of the request as soon as any required orchestrator-owned prerequisites are ready. Before that call, use `ask-user` only to choose a supported channel or to define a workflow or data-table prerequisite that the orchestrator must create. Only ask about the channel after `list-agent-capabilities` shows that the requested channel is unsupported. Do not collect model, service, tool, topic, schedule, credential, or other Agent implementation choices first. The embedded Agent Builder asks those questions through the `build-agent` call.

When the conversation opens from an existing Agent in the editor and the user asks to change its configuration or capabilities, that is an agent-anchored request — target that Agent and call `build-agent`. Do not reroute to `workflow-builder`, and do not spawn a workflow to satisfy a capability change on the Agent.

Supported channels & unsupported requests

`list-agent-capabilities` returns every chat channel n8n Agents support, each with `capabilities`, `useIntegrationWhen`, and `useNodeToolWhen`. It is the authoritative source the orchestrator can read before building; a channel absent from its result is unsupported for agents.

When the user asks for a channel that is not supported (e.g. WhatsApp, Microsoft Teams), do not forward it to the builder as a channel to configure and do not fake it by adding the platform as an agent tool. Explain the channel is unsupported for agents, offer the supported alternatives, and ask which to use — or whether the user explicitly wants that unsupported platform as the conversation surface, in which case offer the `agent-entrypoint` workflow bridge described in Prerequisites (it connects the platform trigger to Message an Agent; it is not a channel config). Only forward a channel to `build-agent` once it is a supported type or the user has chosen an alternative.

Faithful handoff

Treat `message` as a faithful handoff of the user's request, not an Agent build specification authored by you. Forward the user's wording as close to verbatim as possible. Include only:

• Requirements, constraints, and implementation choices the user explicitly

stated.

• Explicit answers or decisions from earlier turns that are necessary for the

current request.

• Prerequisite workflows or data tables you created for this Agent.

Never infer, invent, expand, recommend, or prescribe implementation details the user did not request, and never present your assumptions as user requirements. In particular, do not choose or tell the builder which model, instructions, tools, tool types, integrations, channels, MCP servers, workflows, skills, tasks, memory, credentials, triggers, schedules, approvals, or test strategy to use.

Do not translate an outcome or named service into a specific implementation. For example, forward "a Slack agent that says hello to me" without turning it into a request for a Slack node tool. Preserve unspecified and ambiguous implementation details so the builder can resolve them with its own guidance and interactive tools.

Prerequisites

Before the first `build-agent` call, create prerequisites the builder cannot create when they must be attached to or used by the Agent:

• Create a workflow tool only when one Agent tool call must run an ordered

multi-node procedure, or when the user explicitly needs that workflow to be reusable, manually callable, or usable outside the Agent. Follow `workflow-builder`, then pass the built workflow in `workflowContext`.

• When the Agent will store or query tabular data, follow `data-table-manager`

and create the required tables via `data-tables`. The builder cannot create tables.

List prerequisite names and schemas in `message`. Let the builder gather the remaining Agent-specific requirements, including model, credentials, integrations, and direct tools.

`build-agent` can return structured `requiredArtifacts` when the embedded builder discovers something Instance AI must create:

• For a workflow with `relationship: "agent-tool"`, build it, pass it in

`workflowContext`, and call `build-agent` again so the builder can attach it.

• For a workflow with `relationship: "agent-entrypoint"`, build it after the

Agent exists, using the returned `agentId`. This workflow invokes the Agent; never pass it in `workflowContext`, never attach it to the Agent as a tool, and do not call `build-agent` again solely to attach it.

• For a data table, create it and call `build-agent` again with its name and

schema in `message`.

For an unsupported chat channel, an `agent-entrypoint` workflow should connect the platform trigger to Message an Agent, map the incoming message, use a stable platform conversation/sender identifier as the custom session key, and send the Agent's `text` response through the platform. Native Agent channels do not need this wrapper.

If an older builder only lists missing workflows or tables in `builderReply`, handle them the same way based on whether the workflow calls the Agent or is called by the Agent. Never ask the user to create prerequisi