erstan-agent-builder

erstan-agent-builder is a skill for Claude Code, Codex from erstanai/erstan-agent-tools-beta. It costs 63 tokens per session (778 once invoked), scanned A, original, Apache-2.0.

Instructions for creating and changing Erstan Agent graphs. A graph is a workflow made of connected steps, tools, instructions, and rules.

In plain words
What is it for?
Building, revising, validating, testing, previewing, configuring, and publishing Erstan Agents.
Why use it?
They help keep Agent changes valid, complete, and separate from later testing or publication decisions.

Skill for Claude CodeCodex

Written for Claude Code and Codex: shipped in a Claude Code plugin, but also agents/openai.yaml present.

Part of the erstan-beta plugin — 7 skills, 1 MCP server shipped together

Good fit Building, revising, validating, testing, previewing, configuring, and publishing Erstan Agents.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/erstanai/erstan-agent-tools-beta/erstan-agent-builder
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add erstanai/erstan-agent-tools-beta --skill erstan-agent-builder
Clone the repo
git clone --depth 1 https://github.com/erstanai/erstan-agent-tools-beta

Made for: Claude Code, Codex.

Or install erstan-beta, the plugin that ships this one along with the rest of its 7 skills, 1 MCP server.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for erstan-agent-builder

README.md
[![agentmods](https://agentmods.dev/badge/skills/erstanai/erstan-agent-tools-beta/erstan-agent-builder.svg)](https://agentmods.dev/skills/erstanai/erstan-agent-tools-beta/erstan-agent-builder)
Your own site
<a href="https://agentmods.dev/skills/erstanai/erstan-agent-tools-beta/erstan-agent-builder"><img src="https://agentmods.dev/badge/skills/erstanai/erstan-agent-tools-beta/erstan-agent-builder.svg" alt="Measured on agentmods" height="20"></a>
Per session 63 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 778 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00063 $0.00778
Opus 5 $0.00032 $0.00389
Sonnet 5 $0.00013 $0.00156
Haiku 4.5 $0.00006 $0.00078

Measured 7d ago against content hash 7d33356d17c3, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

erstan-agent-builder scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

plugins/erstan-beta/skills/erstan-agent-builder/SKILL.md · 64 lines

How it starts

The opening of the file, as written. The whole thing — 64 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Erstan Agent builder

Build against the live Erstan authoring contract. Treat creation, update, testing, and publication as separate lifecycle actions.

Reference

Read lifecycle and graph rules before creating or changing a graph. The live guide, node catalog, and tool schemas remain authoritative when that reference differs.

Workflow

  1. Establish the intended Agent behavior, owner team, inputs, outputs, tool and Skill needs, and whether the request authorizes only a proposal, a saved draft, a live preview, or publication.
  2. Call get_agent_builder_guide, then get_agent_node_catalog with the detail needed for every proposed node. Call list_agent_tools and list_agent_skills before choosing bindings. Never invent a node field, action type, tool, Skill ID, connection ID, or policy value.
  3. For an existing Agent, call get_agent and retain its complete graph, currentVersion, published state, and opaque revision. Preserve unrelated metadata, nodes, edges, positions, and bindings.
  4. Assemble the complete candidate graph. Use canonical node types and an explicit top-level data.toolPolicy on every tool-capable AI node. Pin every capability required for deterministic or write-capable work.
  5. Run validate_agent against the candidate or saved draft before a write when the live schema supports that path. Resolve errors within the requested scope. Report unrelated pre-existing errors instead of silently expanding the change.
  6. Use create_agent for a new draft or update_agent with the latest revision for an existing draft. Re-read or use the returned revision after every successful mutation.
  7. Validate the persisted draft. Treat valid: false as a failed validation even when the MCP call itself succeeded.
  8. Call test_agent only when the user explicitly authorizes a live preview. Preview uses real tools and may create external effects.
  9. Call publish_agent only after an explicit publication request, successful validation, and a final check that the exact current revision is intended. Never describe a draft as published unless the tool confirms publication.

Read the full file on GitHub · 64 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 7d ago First seen · 64 lines · 63 tokens per session scan A 7d33356d17c3

Subscribe to this mod's changes

erstan-agent-builder is a skill published in the GitHub repository erstanai/erstan-agent-tools-beta (0 stars, last pushed 9d ago), licensed Apache-2.0. It adds 63 tokens to every session and 778 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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