hermes-agent/tools/skills_tool.py
kshitij f210510276 feat: add prerequisites field to skill spec — hide skills with unmet dependencies
Skills can now declare runtime prerequisites (env vars, CLI binaries) via
YAML frontmatter. Skills with unmet prerequisites are excluded from the
system prompt so the agent never claims capabilities it can't deliver, and
skill_view() warns the agent about what's missing.

Three layers of defense:
- build_skills_system_prompt() filters out unavailable skills
- _find_all_skills() flags unmet prerequisites in metadata
- skill_view() returns prerequisites_warning with actionable details

Tagged 12 bundled skills that have hard runtime dependencies:
gif-search (TENOR_API_KEY), notion (NOTION_API_KEY), himalaya, imessage,
apple-notes, apple-reminders, openhue, duckduckgo-search, codebase-inspection,
blogwatcher, songsee, mcporter.

Closes #658
Fixes #630
2026-03-08 13:19:32 +05:30

823 lines
31 KiB
Python

#!/usr/bin/env python3
"""
Skills Tool Module
This module provides tools for listing and viewing skill documents.
Skills are organized as directories containing a SKILL.md file (the main instructions)
and optional supporting files like references, templates, and examples.
Inspired by Anthropic's Claude Skills system with progressive disclosure architecture:
- Metadata (name ≤64 chars, description ≤1024 chars) - shown in skills_list
- Full Instructions - loaded via skill_view when needed
- Linked Files (references, templates) - loaded on demand
Directory Structure:
skills/
├── my-skill/
│ ├── SKILL.md # Main instructions (required)
│ ├── references/ # Supporting documentation
│ │ ├── api.md
│ │ └── examples.md
│ ├── templates/ # Templates for output
│ │ └── template.md
│ └── assets/ # Supplementary files (agentskills.io standard)
└── category/ # Category folder for organization
└── another-skill/
└── SKILL.md
SKILL.md Format (YAML Frontmatter, agentskills.io compatible):
---
name: skill-name # Required, max 64 chars
description: Brief description # Required, max 1024 chars
version: 1.0.0 # Optional
license: MIT # Optional (agentskills.io)
platforms: [macos] # Optional — restrict to specific OS platforms
# Valid: macos, linux, windows
# Omit to load on all platforms (default)
prerequisites: # Optional — runtime requirements
env_vars: [API_KEY] # Env vars that must be set (checked via os.getenv)
commands: [curl, jq] # CLI binaries that must be on PATH (checked via shutil.which)
# Skills with unmet prerequisites are hidden from the
# system prompt and flagged with a warning in skill_view.
compatibility: Requires X # Optional (agentskills.io)
metadata: # Optional, arbitrary key-value (agentskills.io)
hermes:
tags: [fine-tuning, llm]
related_skills: [peft, lora]
---
# Skill Title
Full instructions and content here...
Available tools:
- skills_list: List skills with metadata (progressive disclosure tier 1)
- skill_view: Load full skill content (progressive disclosure tier 2-3)
Usage:
from tools.skills_tool import skills_list, skill_view, check_skills_requirements
# List all skills (returns metadata only - token efficient)
result = skills_list()
# View a skill's main content (loads full instructions)
content = skill_view("axolotl")
# View a reference file within a skill (loads linked file)
content = skill_view("axolotl", "references/dataset-formats.md")
"""
import json
import os
import re
import shutil
import sys
from pathlib import Path
from typing import Dict, Any, List, Optional, Tuple
import yaml
# All skills live in ~/.hermes/skills/ (seeded from bundled skills/ on install).
# This is the single source of truth -- agent edits, hub installs, and bundled
# skills all coexist here without polluting the git repo.
HERMES_HOME = Path(os.getenv("HERMES_HOME", Path.home() / ".hermes"))
SKILLS_DIR = HERMES_HOME / "skills"
# Anthropic-recommended limits for progressive disclosure efficiency
MAX_NAME_LENGTH = 64
MAX_DESCRIPTION_LENGTH = 1024
# Platform identifiers for the 'platforms' frontmatter field.
# Maps user-friendly names to sys.platform prefixes.
_PLATFORM_MAP = {
"macos": "darwin",
"linux": "linux",
"windows": "win32",
}
def skill_matches_platform(frontmatter: Dict[str, Any]) -> bool:
"""Check if a skill is compatible with the current OS platform.
Skills declare platform requirements via a top-level ``platforms`` list
in their YAML frontmatter::
platforms: [macos] # macOS only
platforms: [macos, linux] # macOS and Linux
Valid values: ``macos``, ``linux``, ``windows``.
If the field is absent or empty the skill is compatible with **all**
platforms (backward-compatible default).
"""
platforms = frontmatter.get("platforms")
if not platforms:
return True # No restriction → loads everywhere
if not isinstance(platforms, list):
platforms = [platforms]
current = sys.platform
for p in platforms:
mapped = _PLATFORM_MAP.get(str(p).lower().strip(), str(p).lower().strip())
if current.startswith(mapped):
return True
return False
def check_skill_prerequisites(frontmatter: Dict[str, Any]) -> Tuple[bool, List[str]]:
"""Check if a skill's declared prerequisites are satisfied.
Skills declare prerequisites via a top-level ``prerequisites`` dict
in their YAML frontmatter::
prerequisites:
env_vars: [TENOR_API_KEY]
commands: [curl, jq]
Returns:
(all_met, missing) — True + empty list if all met, else False + list
of human-readable descriptions of what's missing.
"""
prereqs = frontmatter.get("prerequisites")
if not prereqs or not isinstance(prereqs, dict):
return True, []
missing: List[str] = []
env_vars = prereqs.get("env_vars") or []
if isinstance(env_vars, str):
env_vars = [env_vars]
for var in env_vars:
if not os.getenv(str(var)):
missing.append(f"env ${var}")
commands = prereqs.get("commands") or []
if isinstance(commands, str):
commands = [commands]
for cmd in commands:
if not shutil.which(str(cmd)):
missing.append(f"command `{cmd}`")
return (len(missing) == 0), missing
def check_skills_requirements() -> bool:
"""Skills are always available -- the directory is created on first use if needed."""
return True
def _parse_frontmatter(content: str) -> Tuple[Dict[str, Any], str]:
"""
Parse YAML frontmatter from markdown content.
Uses yaml.safe_load for full YAML support (nested metadata, lists, etc.)
with a fallback to simple key:value splitting for robustness.
Args:
content: Full markdown file content
Returns:
Tuple of (frontmatter dict, remaining content)
"""
frontmatter = {}
body = content
if content.startswith("---"):
end_match = re.search(r'\n---\s*\n', content[3:])
if end_match:
yaml_content = content[3:end_match.start() + 3]
body = content[end_match.end() + 3:]
try:
parsed = yaml.safe_load(yaml_content)
if isinstance(parsed, dict):
frontmatter = parsed
# yaml.safe_load returns None for empty frontmatter
except yaml.YAMLError:
# Fallback: simple key:value parsing for malformed YAML
for line in yaml_content.strip().split('\n'):
if ':' in line:
key, value = line.split(':', 1)
frontmatter[key.strip()] = value.strip()
return frontmatter, body
def _get_category_from_path(skill_path: Path) -> Optional[str]:
"""
Extract category from skill path based on directory structure.
For paths like: ~/.hermes/skills/mlops/axolotl/SKILL.md -> "mlops"
"""
try:
rel_path = skill_path.relative_to(SKILLS_DIR)
parts = rel_path.parts
if len(parts) >= 3:
return parts[0]
return None
except ValueError:
return None
def _estimate_tokens(content: str) -> int:
"""
Rough token estimate (4 chars per token average).
Args:
content: Text content
Returns:
Estimated token count
"""
return len(content) // 4
def _parse_tags(tags_value) -> List[str]:
"""
Parse tags from frontmatter value.
Handles:
- Already-parsed list (from yaml.safe_load): [tag1, tag2]
- String with brackets: "[tag1, tag2]"
- Comma-separated string: "tag1, tag2"
Args:
tags_value: Raw tags value — may be a list or string
Returns:
List of tag strings
"""
if not tags_value:
return []
# yaml.safe_load already returns a list for [tag1, tag2]
if isinstance(tags_value, list):
return [str(t).strip() for t in tags_value if t]
# String fallback — handle bracket-wrapped or comma-separated
tags_value = str(tags_value).strip()
if tags_value.startswith('[') and tags_value.endswith(']'):
tags_value = tags_value[1:-1]
return [t.strip().strip('"\'') for t in tags_value.split(',') if t.strip()]
def _find_all_skills() -> List[Dict[str, Any]]:
"""
Recursively find all skills in ~/.hermes/skills/.
Returns metadata for progressive disclosure (tier 1):
- name, description, category
Returns:
List of skill metadata dicts
"""
skills = []
if not SKILLS_DIR.exists():
return skills
for skill_md in SKILLS_DIR.rglob("SKILL.md"):
if any(part in ('.git', '.github', '.hub') for part in skill_md.parts):
continue
skill_dir = skill_md.parent
try:
content = skill_md.read_text(encoding='utf-8')
frontmatter, body = _parse_frontmatter(content)
# Skip skills incompatible with the current OS platform
if not skill_matches_platform(frontmatter):
continue
name = frontmatter.get('name', skill_dir.name)[:MAX_NAME_LENGTH]
description = frontmatter.get('description', '')
if not description:
for line in body.strip().split('\n'):
line = line.strip()
if line and not line.startswith('#'):
description = line
break
if len(description) > MAX_DESCRIPTION_LENGTH:
description = description[:MAX_DESCRIPTION_LENGTH - 3] + "..."
category = _get_category_from_path(skill_md)
prereqs_met, prereqs_missing = check_skill_prerequisites(frontmatter)
entry = {
"name": name,
"description": description,
"category": category,
}
if not prereqs_met:
entry["prerequisites_met"] = False
entry["prerequisites_missing"] = prereqs_missing
skills.append(entry)
except Exception:
continue
return skills
def _load_category_description(category_dir: Path) -> Optional[str]:
"""
Load category description from DESCRIPTION.md if it exists.
Args:
category_dir: Path to the category directory
Returns:
Description string or None if not found
"""
desc_file = category_dir / "DESCRIPTION.md"
if not desc_file.exists():
return None
try:
content = desc_file.read_text(encoding='utf-8')
# Parse frontmatter if present
frontmatter, body = _parse_frontmatter(content)
# Prefer frontmatter description, fall back to first non-header line
description = frontmatter.get('description', '')
if not description:
for line in body.strip().split('\n'):
line = line.strip()
if line and not line.startswith('#'):
description = line
break
# Truncate to reasonable length
if len(description) > MAX_DESCRIPTION_LENGTH:
description = description[:MAX_DESCRIPTION_LENGTH - 3] + "..."
return description if description else None
except Exception:
return None
def skills_categories(verbose: bool = False, task_id: str = None) -> str:
"""
List available skill categories with descriptions (progressive disclosure tier 0).
Returns category names and descriptions for efficient discovery before drilling down.
Categories can have a DESCRIPTION.md file with a description frontmatter field
or first paragraph to explain what skills are in that category.
Args:
verbose: If True, include skill counts per category (default: False, but currently always included)
task_id: Optional task identifier (unused, for API consistency)
Returns:
JSON string with list of categories and their descriptions
"""
try:
if not SKILLS_DIR.exists():
return json.dumps({
"success": True,
"categories": [],
"message": "No skills directory found."
}, ensure_ascii=False)
category_dirs = {}
for skill_md in SKILLS_DIR.rglob("SKILL.md"):
category = _get_category_from_path(skill_md)
if category:
category_dir = SKILLS_DIR / category
if category not in category_dirs:
category_dirs[category] = category_dir
categories = []
for name in sorted(category_dirs.keys()):
category_dir = category_dirs[name]
description = _load_category_description(category_dir)
skill_count = sum(1 for _ in category_dir.rglob("SKILL.md"))
cat_entry = {"name": name, "skill_count": skill_count}
if description:
cat_entry["description"] = description
categories.append(cat_entry)
return json.dumps({
"success": True,
"categories": categories,
"hint": "If a category is relevant to your task, use skills_list with that category to see available skills"
}, ensure_ascii=False)
except Exception as e:
return json.dumps({
"success": False,
"error": str(e)
}, ensure_ascii=False)
def skills_list(category: str = None, task_id: str = None) -> str:
"""
List all available skills (progressive disclosure tier 1 - minimal metadata).
Returns only name + description to minimize token usage. Use skill_view() to
load full content, tags, related files, etc.
Args:
category: Optional category filter (e.g., "mlops")
task_id: Optional task identifier (unused, for API consistency)
Returns:
JSON string with minimal skill info: name, description, category
"""
try:
if not SKILLS_DIR.exists():
SKILLS_DIR.mkdir(parents=True, exist_ok=True)
return json.dumps({
"success": True,
"skills": [],
"categories": [],
"message": "No skills found. Skills directory created at ~/.hermes/skills/"
}, ensure_ascii=False)
# Find all skills
all_skills = _find_all_skills()
if not all_skills:
return json.dumps({
"success": True,
"skills": [],
"categories": [],
"message": "No skills found in skills/ directory."
}, ensure_ascii=False)
# Filter by category if specified
if category:
all_skills = [s for s in all_skills if s.get("category") == category]
# Sort by category then name
all_skills.sort(key=lambda s: (s.get("category") or "", s["name"]))
# Extract unique categories
categories = sorted(set(s.get("category") for s in all_skills if s.get("category")))
return json.dumps({
"success": True,
"skills": all_skills,
"categories": categories,
"count": len(all_skills),
"hint": "Use skill_view(name) to see full content, tags, and linked files"
}, ensure_ascii=False)
except Exception as e:
return json.dumps({
"success": False,
"error": str(e)
}, ensure_ascii=False)
def skill_view(name: str, file_path: str = None, task_id: str = None) -> str:
"""
View the content of a skill or a specific file within a skill directory.
Args:
name: Name or path of the skill (e.g., "axolotl" or "03-fine-tuning/axolotl")
file_path: Optional path to a specific file within the skill (e.g., "references/api.md")
task_id: Optional task identifier (unused, for API consistency)
Returns:
JSON string with skill content or error message
"""
try:
if not SKILLS_DIR.exists():
return json.dumps({
"success": False,
"error": "Skills directory does not exist yet. It will be created on first install."
}, ensure_ascii=False)
skill_dir = None
skill_md = None
# Try direct path first (e.g., "mlops/axolotl")
direct_path = SKILLS_DIR / name
if direct_path.is_dir() and (direct_path / "SKILL.md").exists():
skill_dir = direct_path
skill_md = direct_path / "SKILL.md"
elif direct_path.with_suffix('.md').exists():
skill_md = direct_path.with_suffix('.md')
# Search by directory name
if not skill_md:
for found_skill_md in SKILLS_DIR.rglob("SKILL.md"):
if found_skill_md.parent.name == name:
skill_dir = found_skill_md.parent
skill_md = found_skill_md
break
# Legacy: flat .md files
if not skill_md:
for found_md in SKILLS_DIR.rglob(f"{name}.md"):
if found_md.name != "SKILL.md":
skill_md = found_md
break
if not skill_md or not skill_md.exists():
# List available skills in error message
all_skills = _find_all_skills()
available = [s["name"] for s in all_skills[:20]] # Limit to 20
return json.dumps({
"success": False,
"error": f"Skill '{name}' not found.",
"available_skills": available,
"hint": "Use skills_list to see all available skills"
}, ensure_ascii=False)
# If a specific file path is requested, read that instead
if file_path and skill_dir:
# Security: Prevent path traversal attacks
normalized_path = Path(file_path)
if ".." in normalized_path.parts:
return json.dumps({
"success": False,
"error": "Path traversal ('..') is not allowed.",
"hint": "Use a relative path within the skill directory"
}, ensure_ascii=False)
target_file = skill_dir / file_path
# Security: Verify resolved path is still within skill directory
try:
resolved = target_file.resolve()
skill_dir_resolved = skill_dir.resolve()
if not resolved.is_relative_to(skill_dir_resolved):
return json.dumps({
"success": False,
"error": "Path escapes skill directory boundary.",
"hint": "Use a relative path within the skill directory"
}, ensure_ascii=False)
except (OSError, ValueError):
return json.dumps({
"success": False,
"error": f"Invalid file path: '{file_path}'",
"hint": "Use a valid relative path within the skill directory"
}, ensure_ascii=False)
if not target_file.exists():
# List available files in the skill directory, organized by type
available_files = {
"references": [],
"templates": [],
"assets": [],
"scripts": [],
"other": []
}
# Scan for all readable files
for f in skill_dir.rglob("*"):
if f.is_file() and f.name != "SKILL.md":
rel = str(f.relative_to(skill_dir))
if rel.startswith("references/"):
available_files["references"].append(rel)
elif rel.startswith("templates/"):
available_files["templates"].append(rel)
elif rel.startswith("assets/"):
available_files["assets"].append(rel)
elif rel.startswith("scripts/"):
available_files["scripts"].append(rel)
elif f.suffix in ['.md', '.py', '.yaml', '.yml', '.json', '.tex', '.sh']:
available_files["other"].append(rel)
# Remove empty categories
available_files = {k: v for k, v in available_files.items() if v}
return json.dumps({
"success": False,
"error": f"File '{file_path}' not found in skill '{name}'.",
"available_files": available_files,
"hint": "Use one of the available file paths listed above"
}, ensure_ascii=False)
# Read the file content
try:
content = target_file.read_text(encoding='utf-8')
except UnicodeDecodeError:
# Binary file - return info about it instead
return json.dumps({
"success": True,
"name": name,
"file": file_path,
"content": f"[Binary file: {target_file.name}, size: {target_file.stat().st_size} bytes]",
"is_binary": True
}, ensure_ascii=False)
return json.dumps({
"success": True,
"name": name,
"file": file_path,
"content": content,
"file_type": target_file.suffix
}, ensure_ascii=False)
# Read the main skill content
content = skill_md.read_text(encoding='utf-8')
frontmatter, body = _parse_frontmatter(content)
# Get reference, template, asset, and script files if this is a directory-based skill
reference_files = []
template_files = []
asset_files = []
script_files = []
if skill_dir:
references_dir = skill_dir / "references"
if references_dir.exists():
reference_files = [str(f.relative_to(skill_dir)) for f in references_dir.glob("*.md")]
templates_dir = skill_dir / "templates"
if templates_dir.exists():
for ext in ['*.md', '*.py', '*.yaml', '*.yml', '*.json', '*.tex', '*.sh']:
template_files.extend([str(f.relative_to(skill_dir)) for f in templates_dir.rglob(ext)])
# assets/ — agentskills.io standard directory for supplementary files
assets_dir = skill_dir / "assets"
if assets_dir.exists():
for f in assets_dir.rglob("*"):
if f.is_file():
asset_files.append(str(f.relative_to(skill_dir)))
scripts_dir = skill_dir / "scripts"
if scripts_dir.exists():
for ext in ['*.py', '*.sh', '*.bash', '*.js', '*.ts', '*.rb']:
script_files.extend([str(f.relative_to(skill_dir)) for f in scripts_dir.glob(ext)])
# Read tags/related_skills with backward compat:
# Check metadata.hermes.* first (agentskills.io convention), fall back to top-level
hermes_meta = {}
metadata = frontmatter.get('metadata')
if isinstance(metadata, dict):
hermes_meta = metadata.get('hermes', {}) or {}
tags = _parse_tags(hermes_meta.get('tags') or frontmatter.get('tags', ''))
related_skills = _parse_tags(hermes_meta.get('related_skills') or frontmatter.get('related_skills', ''))
# Build linked files structure for clear discovery
linked_files = {}
if reference_files:
linked_files["references"] = reference_files
if template_files:
linked_files["templates"] = template_files
if asset_files:
linked_files["assets"] = asset_files
if script_files:
linked_files["scripts"] = script_files
rel_path = str(skill_md.relative_to(SKILLS_DIR))
result = {
"success": True,
"name": frontmatter.get('name', skill_md.stem if not skill_dir else skill_dir.name),
"description": frontmatter.get('description', ''),
"tags": tags,
"related_skills": related_skills,
"content": content,
"path": rel_path,
"linked_files": linked_files if linked_files else None,
"usage_hint": "To view linked files, call skill_view(name, file_path) where file_path is e.g. 'references/api.md' or 'assets/config.yaml'" if linked_files else None
}
# Prerequisite check — warn the agent if requirements are unmet
prereqs_met, prereqs_missing = check_skill_prerequisites(frontmatter)
if not prereqs_met:
result["prerequisites_met"] = False
result["prerequisites_missing"] = prereqs_missing
result["prerequisites_warning"] = (
f"This skill requires {', '.join(prereqs_missing)} which "
f"{'is' if len(prereqs_missing) == 1 else 'are'} not available. "
f"Tell the user what's needed before attempting to use this skill."
)
# Surface agentskills.io optional fields when present
if frontmatter.get('compatibility'):
result["compatibility"] = frontmatter['compatibility']
if isinstance(metadata, dict):
result["metadata"] = metadata
return json.dumps(result, ensure_ascii=False)
except Exception as e:
return json.dumps({
"success": False,
"error": str(e)
}, ensure_ascii=False)
# Tool description for model_tools.py
SKILLS_TOOL_DESCRIPTION = """Access skill documents providing specialized instructions, guidelines, and executable knowledge.
Progressive disclosure workflow:
1. skills_list() - Returns metadata (name, description, tags, linked_file_count) for all skills
2. skill_view(name) - Loads full SKILL.md content + shows available linked_files
3. skill_view(name, file_path) - Loads specific linked file (e.g., 'references/api.md', 'scripts/train.py')
Skills may include:
- references/: Additional documentation, API specs, examples
- templates/: Output formats, config files, boilerplate code
- assets/: Supplementary files (agentskills.io standard)
- scripts/: Executable helpers (Python, shell scripts)"""
if __name__ == "__main__":
"""Test the skills tool"""
print("🎯 Skills Tool Test")
print("=" * 60)
# Test listing skills
print("\n📋 Listing all skills:")
result = json.loads(skills_list())
if result["success"]:
print(f"Found {result['count']} skills in {len(result.get('categories', []))} categories")
print(f"Categories: {result.get('categories', [])}")
print("\nFirst 10 skills:")
for skill in result["skills"][:10]:
cat = f"[{skill['category']}] " if skill.get('category') else ""
refs = f" (+{len(skill['reference_files'])} refs)" if skill.get('reference_files') else ""
print(f"{cat}{skill['name']}: {skill['description'][:60]}...{refs}")
else:
print(f"Error: {result['error']}")
# Test viewing a skill
print("\n📖 Viewing skill 'axolotl':")
result = json.loads(skill_view("axolotl"))
if result["success"]:
print(f"Name: {result['name']}")
print(f"Description: {result.get('description', 'N/A')[:100]}...")
print(f"Content length: {len(result['content'])} chars")
if result.get('reference_files'):
print(f"Reference files: {result['reference_files']}")
else:
print(f"Error: {result['error']}")
# Test viewing a reference file
print("\n📄 Viewing reference file 'axolotl/references/dataset-formats.md':")
result = json.loads(skill_view("axolotl", "references/dataset-formats.md"))
if result["success"]:
print(f"File: {result['file']}")
print(f"Content length: {len(result['content'])} chars")
print(f"Preview: {result['content'][:150]}...")
else:
print(f"Error: {result['error']}")
# ---------------------------------------------------------------------------
# Registry
# ---------------------------------------------------------------------------
from tools.registry import registry
SKILLS_LIST_SCHEMA = {
"name": "skills_list",
"description": "List available skills (name + description). Use skill_view(name) to load full content.",
"parameters": {
"type": "object",
"properties": {
"category": {
"type": "string",
"description": "Optional category filter to narrow results"
}
},
"required": []
}
}
SKILL_VIEW_SCHEMA = {
"name": "skill_view",
"description": "Skills allow for loading information about specific tasks and workflows, as well as scripts and templates. Load a skill's full content or access its linked files (references, templates, scripts). First call returns SKILL.md content plus a 'linked_files' dict showing available references/templates/scripts. To access those, call again with file_path parameter.",
"parameters": {
"type": "object",
"properties": {
"name": {
"type": "string",
"description": "The skill name (use skills_list to see available skills)"
},
"file_path": {
"type": "string",
"description": "OPTIONAL: Path to a linked file within the skill (e.g., 'references/api.md', 'templates/config.yaml', 'scripts/validate.py'). Omit to get the main SKILL.md content."
}
},
"required": ["name"]
}
}
registry.register(
name="skills_list",
toolset="skills",
schema=SKILLS_LIST_SCHEMA,
handler=lambda args, **kw: skills_list(category=args.get("category")),
check_fn=check_skills_requirements,
)
registry.register(
name="skill_view",
toolset="skills",
schema=SKILL_VIEW_SCHEMA,
handler=lambda args, **kw: skill_view(args.get("name", ""), file_path=args.get("file_path")),
check_fn=check_skills_requirements,
)