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| name | description | version | author | license | platforms | metadata | ||||||||||||||||
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| hermes-agent-skill-authoring | Author in-repo SKILL.md: frontmatter, validator, structure, and writing-quality principles. | 1.1.0 | Hermes Agent | MIT |
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Authoring Hermes-Agent Skills (in-repo)
Overview
There are two places a SKILL.md can live:
- User-local:
~/.hermes/skills/<maybe-category>/<name>/SKILL.md— personal, not shared. Created viaskill_manage(action='create'). - In-repo (this skill is about this case):
/home/bb/hermes-agent/skills/<category>/<name>/SKILL.md— committed, shipped with the package. Usewrite_file+git add.skill_manage(action='create')does NOT target this tree.
When to Use
- User asks you to add a skill "in this branch / repo / commit"
- You're committing a reusable workflow that should ship with hermes-agent
- You're editing an existing skill under
/home/bb/hermes-agent/skills/(usepatchfor small edits,write_filefor rewrites;skill_managestill works for patch on in-repo skills, but not forcreate)
Required Frontmatter
Source of truth: tools/skill_manager_tool.py::_validate_frontmatter. Hard requirements:
- Starts with
---as the first bytes (no leading blank line). - Closes with
\n---\nbefore the body. - Parses as a YAML mapping.
namefield present.descriptionfield present, ≤ 1024 chars (MAX_DESCRIPTION_LENGTH).- Non-empty body after the closing
---.
Peer-matched shape used by every skill under skills/software-development/:
---
name: my-skill-name # lowercase, hyphens, ≤64 chars (MAX_NAME_LENGTH)
description: Use when <trigger>. <one-line behavior>.
version: 1.1.0
author: Hermes Agent
license: MIT
metadata:
hermes:
tags: [short, descriptive, tags]
related_skills: [other-skill, another-skill]
---
version / author / license / metadata are NOT enforced by the validator, but every peer has them — omit and your skill sticks out.
Size Limits
- Description: ≤ 1024 chars (enforced).
- Full SKILL.md: ≤ 100,000 chars (enforced as
MAX_SKILL_CONTENT_CHARS, ~36k tokens). - Peer skills in
software-development/sit at 8-14k chars. Aim for that range. If you're pushing past 20k, split intoreferences/*.mdand reference them from SKILL.md.
Writing Quality Principles
A skill exists to make the agent's process more predictable. Predictability does not mean identical output every run; it means the agent reliably follows the same useful discipline.
Use these quality checks when writing or editing any skill:
- Optimize for process predictability. Ask: what behavior should change when this skill loads? If a line does not change behavior, cut it.
- Choose the right context load. A model-invoked Hermes skill pays for its description every turn. Keep descriptions focused on trigger classes and the skill's distinctive behavior. Put details in the body or linked references.
- Use an information hierarchy. Put always-needed steps in
SKILL.md; put branch-specific or bulky reference material inreferences/,templates/, orscripts/and point to it only when needed. - End steps with completion criteria. Each ordered step should say how the agent knows it is done. Good criteria are checkable and, when it matters, exhaustive: "every modified file accounted for" beats "summarize changes."
- Co-locate rules with the concept they govern. Avoid scattering one idea across the file. Keep definition, caveats, examples, and verification near each other.
- Use strong leading words. Prefer compact concepts the model already knows — e.g. "tight loop," "tracer bullet," "root cause," "regression test" — over long repeated explanations. A good leading word saves tokens and anchors behavior.
- Prune duplication and no-ops. Keep each meaning in one source of truth. Sentence by sentence, ask whether the sentence changes agent behavior versus the default. If not, delete it rather than polishing it.
- Watch for premature completion. If agents tend to rush a step, first sharpen that step's completion criterion. Split the sequence only when later steps distract from doing the current step well.
Common quality failures:
- Premature completion — the skill lets the agent move on before the work is genuinely done.
- Duplication — the same rule appears in multiple places and drifts.
- Sediment — stale lines remain because adding felt safer than deleting.
- Sprawl — too much always-visible material; push branch-specific reference behind pointers.
- No-op prose — generic advice the agent would already follow without the skill.
Peer-Matched Structure
Every in-repo skill follows roughly:
# <Title>
## Overview
One or two paragraphs: what and why.
## When to Use
- Bulleted triggers
- "Don't use for:" counter-triggers
## <Topic sections specific to the skill>
- Quick-reference tables are common
- Code blocks with exact commands
- Hermes-specific recipes (tests via scripts/run_tests.sh, ui-tui paths, etc.)
## Common Pitfalls
Numbered list of mistakes and their fixes.
## Verification Checklist
- [ ] Checkbox list of post-action verifications
## One-Shot Recipes (optional)
Named scenarios → concrete command sequences.
Not every section is mandatory, but Overview + When to Use + actionable body + pitfalls are the minimum for the skill to feel like a peer.
Directory Placement
skills/<category>/<skill-name>/SKILL.md
Categories currently in repo (confirm with ls skills/): autonomous-ai-agents, creative, data-science, devops, dogfood, email, gaming, github, leisure, mcp, media, mlops/*, note-taking, productivity, red-teaming, research, smart-home, social-media, software-development.
Pick the closest existing category. Don't invent new top-level categories casually.
Workflow
- Survey peers in the target category:
Read 2-3 peer SKILL.md files to match tone and structure.ls skills/<category>/ - Check validator constraints in
tools/skill_manager_tool.pyif unsure. - Draft with
write_filetoskills/<category>/<name>/SKILL.md. - Validate locally:
import yaml, re, pathlib content = pathlib.Path("skills/<category>/<name>/SKILL.md").read_text() assert content.startswith("---") m = re.search(r'\n---\s*\n', content[3:]) fm = yaml.safe_load(content[3:m.start()+3]) assert "name" in fm and "description" in fm assert len(fm["description"]) <= 1024 assert len(content) <= 100_000 - Git add + commit on the active branch.
- Note: the CURRENT session's skill loader is cached —
skill_view/skills_listwill not see the new skill until a new session. This is expected, not a bug.
Cross-Referencing Other Skills
metadata.hermes.related_skills unions both trees (skills/ in-repo and ~/.hermes/skills/) at load time. You CAN reference a user-local skill from an in-repo skill, but it won't resolve for other users who clone the repo fresh. Prefer referencing only in-repo skills from in-repo skills. If a frequently-referenced skill lives only in ~/.hermes/skills/, consider promoting it to the repo.
Editing Existing In-Repo Skills
- Small fix (typo, added pitfall, tightened trigger):
skill_manage(action='patch', name=..., old_string=..., new_string=...)works fine on in-repo skills. - Major rewrite:
write_filethe whole SKILL.md.skill_manage(action='edit')also works but requires supplying the full new content. - Adding supporting files:
write_filetoskills/<category>/<name>/references/<file>.md,templates/<file>, orscripts/<file>.skill_manage(action='write_file')also works and enforces the references/templates/scripts/assets subdir allowlist. - Always commit the edit — in-repo skills are source, not runtime state.
Common Pitfalls
-
Using
skill_manage(action='create')for an in-repo skill. It writes to~/.hermes/skills/, not the repo tree. Usewrite_filefor in-repo creation. -
Leading whitespace before
---. The validator checkscontent.startswith("---"); any leading blank line or BOM fails validation. -
Description too generic. Peer descriptions start with "Use when ..." and describe the trigger class, not the one task. "Use when debugging X" > "Debug X".
-
Forgetting the author/license/metadata block. Not validator-enforced, but every peer has it; omitting makes the skill look half-finished.
-
Writing a skill that duplicates a peer. Before creating,
ls skills/<category>/and open 2-3 peers. Prefer extending an existing skill to creating a narrow sibling. -
Expecting the current session to see the new skill. It won't. The skill loader is initialized at session start. Verify in a fresh session or via
skill_viewusing the exact path. -
Letting skills accumulate sediment. A skill should get shorter or sharper over time. When adding a rule, remove the old wording it replaces; don't layer advice forever.
-
Writing no-op prose. "Be careful," "be thorough," and "use best practices" rarely change model behavior. Replace with a checkable completion criterion or a stronger leading word.
-
Linking to skills that don't exist in-repo.
related_skills: [some-user-local-skill]works for you but breaks for other clones. Prefer only in-repo links.
Verification Checklist
- File is at
skills/<category>/<name>/SKILL.md(not in~/.hermes/skills/) - Frontmatter starts at byte 0 with
---, closes with\n---\n name,description,version,author,license,metadata.hermes.{tags, related_skills}all present- Name ≤ 64 chars, lowercase + hyphens
- Description ≤ 1024 chars and starts with "Use when ..."
- Total file ≤ 100,000 chars (aim for 8-15k)
- Structure:
# Title→## Overview→## When to Use→ body →## Common Pitfalls→## Verification Checklist - Each ordered step has a checkable completion criterion
- Description is trigger-focused and avoids duplicated body content
- Bulky or branch-specific reference is progressively disclosed in linked files
- No-op prose and duplicated rules removed
related_skillsreferences resolve in-repo (or are explicitly OK to be user-local)git add skills/<category>/<name>/ && git commitcompleted on the intended branch