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 agentmods add skills/jimmc414/claude-code-plugin-marketplace/error-uxnpx skills add jimmc414/claude-code-plugin-marketplace --skill error-uxgit clone --depth 1 https://github.com/jimmc414/claude-code-plugin-marketplaceWrote 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/jimmc414/claude-code-plugin-marketplace/error-ux)<a href="https://agentmods.dev/skills/jimmc414/claude-code-plugin-marketplace/error-ux"><img src="https://agentmods.dev/badge/skills/jimmc414/claude-code-plugin-marketplace/error-ux.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00000 | $0.01877 |
| Opus 5 | $0.00000 | $0.00938 |
| Sonnet 5 | $0.00000 | $0.00375 |
| Haiku 4.5 | $0.00000 | $0.00188 |
Grade A, and why
error-ux 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 6d 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 — 271 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Error UX Skill
Purpose
Provides principles and patterns for writing error messages that help users recover instead of leaving them stuck.
The Error Message Framework
Every error message should answer three questions:
1. What Happened (Symptom)
State the problem in user terms, not system terms.
| System Speak | User Speak |
|---|---|
ETIMEDOUT |
The request took too long |
ECONNREFUSED |
Cannot connect to the service |
403 Forbidden |
You don't have permission |
ENOMEM |
The system is overloaded |
Deadlock detected |
Please try again in a moment |
ENOENT |
File or resource not found |
EPERM |
Permission denied |
EEXIST |
Already exists |
2. Why It Happened (Cause)
Give the most likely explanation without requiring technical knowledge.
Common causes to surface:
- Network connectivity issues
- Invalid input (be specific about which field)
- Missing permissions
- Resource not found (was it deleted?)
- Rate limiting
- Service temporarily unavailable
- Session expired
- Configuration missing
3. What To Do (Resolution)
Provide concrete next steps. Prioritize:
- Self-service fixes ("Check your internet connection")
- Retry suggestions ("Try again in a few minutes")
- Alternative paths ("Use X instead")
- Support escalation (last resort, with context to provide)
Error Categories and Patterns
Input Validation Errors
Always specify:
- Which field failed
- What was wrong with it
- What format is expected
Bad: "Validation error"
Good: "Phone number must be 10 digits. You entered: 555-123 (7 digits)"
Bad: "Invalid input"
Good: "Email address is invalid: 'not-an-email' is missing the @ symbol"
Bad: "Field required"
Good: "Please enter your last name"
Authentication/Authorization Errors
Be vague enough for security, helpful enough for legitimate users:
Bad: "Invalid password for user [email protected]" // Confirms email exists
Good: "Email or password is incorrect. [Forgot password?]"
Bad: "You don't have admin role" // Leaks role information
Good: "You don't have permission to access this page. Contact your administrator if you need access."
Bad: "Token expired at 2024-01-15T10:30:00" // Leaks timing info
Good: "Your session has expired. Please log in again."
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.
- 6d ago First seen · 271 lines · 0 tokens per session scan A 979e470db1d3
error-ux is a skill published in the GitHub repository jimmc414/claude-code-plugin-marketplace (4 stars, last pushed yesterday), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,877 tokens. 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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Audit and remediate skill-encapsulation violations. External citations reaching into private surfaces inside .claude/skills/ / or plugins/ /skills/ / (marketplace monorepos) beyond the slash invocation. Use when: 'audit encapsulation', 'find skill leaks', 'skill boundary violation', 'who is reaching into ', 'check…
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