Berd is an open-source desktop application for working with AI agents through a graphical interface. It is intended for people who want to use different AI models and an integrated Goose backend from a desktop app. The catalogue entries add agent skills, agents, and instructions for working within Berd.
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.
npx skills add block/berd --skill skill-buildergit clone --depth 1 https://github.com/block/berdWrote 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.
[](https://agentmods.dev/skills/block/berd/skill-builder)<a href="https://agentmods.dev/skills/block/berd/skill-builder"><img src="https://agentmods.dev/badge/skills/block/berd/skill-builder/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/block/berd/skill-builder"><img src="https://agentmods.dev/badge/skills/block/berd/skill-builder.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Rogue Agent · line 29 Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00061 | $0.01038 |
| Opus 5.5 | $0.00024 | $0.00415 |
| Sonnet 5.5 | $0.00012 | $0.00208 |
| Haiku 4.5 | $0.00006 | $0.00104 |
Grade A, and why
skill-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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 142 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Skill Builder
Use this skill when creating, editing, or inspecting Berd skills.
What a Skill Is
A skill is a folder with a required SKILL.md file and optional supporting
resources:
skill-name/
├── SKILL.md
├── scripts/
├── references/
└── assets/
Do not create README.md, CHANGELOG.md, or extra documentation files inside a
skill folder. Skill documentation belongs in SKILL.md or references/.
Storage Decision
Skills can be global or project-local:
- Global:
~/.agents/skills/<skill-name>/SKILL.md - Project-local:
<project>/.agents/skills/<skill-name>/SKILL.md
Default to global unless the user is clearly working in a project directory.
If a project directory is active and the user has not specified scope, ask whether the skill should be saved for this project only or globally for all projects.
Do not ask when intent is clear:
- Project-local: "this repo", "this project", "only here", "project skill"
- Global: "all projects", "global", "personal skill", "always available"
When editing an existing skill, keep it in its current location unless the user explicitly asks to move it.
Format
SKILL.md is UTF-8 Markdown with YAML frontmatter:
---
name: skill-name
description: What the skill does. Use when the user asks to...
---
# Skill Title
Instructions the agent follows.
Required frontmatter keys are name and description. Preserve unknown
frontmatter keys when editing existing skills unless the user explicitly asks to
change them.
The description is the trigger surface. It must explain both what the skill
does and when to use it. Include concrete user phrases or task types. Keep it
specific enough to avoid triggering for unrelated work.
Names
Skill names and folder names must match.
Use lowercase kebab-case:
- Allowed:
a-z,0-9, and- - Maximum: 64 characters
- Do not start or end with
- - Do not use spaces, underscores, slashes, or capitals
Normalize user-provided titles by lowercasing, replacing invalid character runs
with -, collapsing repeated separators when practical, trimming leading and
trailing -, and truncating to 64 characters. Fall back to skill if needed.
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.
- 1mo ago First seen · 142 lines · 61 tokens per session scan A 8fc80e9306fe
skill-builder is a skill published in the GitHub repository block/berd (1,007 stars, last pushed 2d ago), licensed Apache-2.0. It adds 61 tokens to every session and 1,038 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-08-30.
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