agent-tool-builder
Tools are how AI agents interact with the world. A well-designed tool is the difference between an agent that works and one that hallucinates, fails silently, or costs 10x more tokens than necessary. This skill covers tool design from schema to error handling. JSON Schema best practices, description writing that actually helps the LLM, validation, and the emerging MCP standard that's becoming the lingua franca for AI tools. Key insight: Tool descriptions are more important than tool implementa
Overall
score
34%
Does it follow best practices?
Validation for skill structure
Install with Tessl CLI
npx tessl i github:sickn33/antigravity-awesome-skills --skill agent-tool-builderActivation
33%This description reads like marketing copy or a course syllabus rather than a functional skill description. It contains conceptual explanations ('Key insight: Tool descriptions are more important...') instead of actionable guidance, lacks explicit trigger conditions, and appears to be truncated. The description would benefit from concrete actions and clear 'Use when' guidance.
Suggestions
Add an explicit 'Use when...' clause with trigger phrases like 'designing tools', 'creating MCP tools', 'writing tool schemas', 'function definitions for AI'
Replace conceptual explanations with concrete actions: 'Designs tool schemas, writes effective tool descriptions, implements MCP-compliant tools, validates tool definitions'
Remove the editorial commentary ('Key insight...') and ensure the description is complete (currently truncated)
| Dimension | Reasoning | Score |
|---|---|---|
Specificity | Names the domain (tool design for AI agents) and mentions some actions like 'JSON Schema best practices, description writing, validation' but these are topics rather than concrete actions Claude would perform. Missing specific verbs like 'create', 'validate', 'generate'. | 2 / 3 |
Completeness | Describes what the skill covers (tool design concepts) but completely lacks a 'Use when...' clause or any explicit trigger guidance. The description reads more like a course overview than actionable skill guidance. Also appears truncated mid-sentence. | 1 / 3 |
Trigger Term Quality | Includes some relevant terms like 'tool design', 'JSON Schema', 'MCP standard', 'error handling', but missing common user phrases like 'create a tool', 'write tool schema', 'define function', 'API definition'. Terms are more conceptual than what users would naturally say. | 2 / 3 |
Distinctiveness Conflict Risk | The focus on AI tool design and MCP standard provides some distinctiveness, but 'JSON Schema' and 'validation' could overlap with general API or schema-related skills. The broad framing around 'how AI agents interact with the world' is quite generic. | 2 / 3 |
Total | 7 / 12 Passed |
Implementation
15%This skill is essentially an empty template with section headers but no substantive content. While the framing text hints at valuable insights about tool design, the actual instructional content (patterns, anti-patterns, examples) is completely missing. The skill cannot guide Claude to build effective agent tools in its current state.
Suggestions
Add concrete JSON Schema examples under 'Tool Schema Design' showing good vs bad schema patterns with actual code
Provide executable code examples for tool error handling that demonstrate returning actionable error messages to LLMs
Fill in the anti-patterns with specific examples showing what vague descriptions and silent failures look like, paired with corrected versions
Either add substantive content to each pattern section or link to separate reference files (e.g., 'See [SCHEMA_EXAMPLES.md](SCHEMA_EXAMPLES.md) for complete patterns')
| Dimension | Reasoning | Score |
|---|---|---|
Conciseness | The content is relatively brief but includes some unnecessary philosophical framing ('You are an expert...', 'Your core insight...') that Claude doesn't need. The capabilities list is redundant given the skill's purpose. | 2 / 3 |
Actionability | The skill provides no concrete code, commands, or executable examples. Section headers like 'Tool Schema Design' and 'Tool Error Handling' are listed but contain no actual guidance, schemas, or implementation details. | 1 / 3 |
Workflow Clarity | No workflow or process is defined. The patterns and anti-patterns sections are empty placeholders with only titles. There are no steps, validation checkpoints, or sequences for building tools. | 1 / 3 |
Progressive Disclosure | The content appears to be a skeleton with empty sections. There are no references to detailed documentation, no links to examples, and the structure suggests content that was never filled in. | 1 / 3 |
Total | 5 / 12 Passed |
Validation
63%Validation — 10 / 16 Passed
Validation for skill structure
| Criteria | Description | Result |
|---|---|---|
description_trigger_hint | Description may be missing an explicit 'when to use' trigger hint (e.g., 'Use when...') | Warning |
metadata_version | 'metadata' field is not a dictionary | Warning |
license_field | 'license' field is missing | Warning |
frontmatter_unknown_keys | Unknown frontmatter key(s) found; consider removing or moving to metadata | Warning |
body_output_format | No obvious output/return/format terms detected; consider specifying expected outputs | Warning |
body_steps | No step-by-step structure detected (no ordered list); consider adding a simple workflow | Warning |
Total | 10 / 16 Passed | |
Reviewed
Table of Contents
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