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 mailgun/mailgun-plugins --skill mcp-troubleshootinggit clone --depth 1 https://github.com/mailgun/mailgun-pluginsWrote 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/mailgun/mailgun-plugins/mcp-troubleshooting)<a href="https://agentmods.dev/skills/mailgun/mailgun-plugins/mcp-troubleshooting"><img src="https://agentmods.dev/badge/skills/mailgun/mailgun-plugins/mcp-troubleshooting/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/mailgun/mailgun-plugins/mcp-troubleshooting"><img src="https://agentmods.dev/badge/skills/mailgun/mailgun-plugins/mcp-troubleshooting.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00030 | $0.00422 |
| Opus 5.5 | $0.00012 | $0.00169 |
| Sonnet 5.5 | $0.00006 | $0.00084 |
| Haiku 4.5 | $0.00003 | $0.00042 |
Grade A, and why
mcp-troubleshooting 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.
What it actually says
MCP Troubleshooting
Use this skill when the user is installing a Mailgun plugin, debugging agent startup, checking why tools are missing, testing a local MCP server, or validating environment configuration.
Use Mailgun workflow skills when the MCP server is running and the user wants to perform account tasks.
Intake
Ask for the host app, plugin package, operating system, whether the issue happens at startup or tool call time, and which environment variables are configured. Do not ask the user to paste secrets.
Workflow
- Confirm
MAILGUN_API_KEYis set in the host environment and that the host was restarted after changes. - Check whether
MAILGUN_API_REGIONis needed for EU accounts. - Check whether
MAILGUN_MCP_TAGSis hiding expected tools. Valid tags aresend,validate,optimize, andinspect. - Verify the plugin config launches
npx -y @mailgun/[email protected]unless the user is intentionally testing a local server build. - For local testing, point the platform MCP config at the built
mailgun-mcp.jsfrom a localmailgun-mcp-servercheckout. - Use the MCP Inspector or the host app's tool listing to confirm which Mailgun tools are exposed.
- Classify failures as missing environment, wrong region, tag filtering, host reload, local build, network/auth, or account permission issues.
Safety
Never ask users to paste API keys into chat or commit secrets to files. If a config example is needed, use placeholder values such as key-... and explain where the user should set the value locally.
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 Changed a7870d219b4e
- 2mo ago First seen · 34 lines · 30 tokens per session scan A e1b3056cd524
mcp-troubleshooting is a skill published in the GitHub repository mailgun/mailgun-plugins (2 stars, last pushed 15d ago), licensed Apache-2.0. It adds 30 tokens to every session and 422 once invoked, about $0.0001 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 2026-08-31.
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