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 cyanheads/evals-mcp-server --skill add-promptgit clone --depth 1 https://github.com/cyanheads/evals-mcp-serverWrote 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/cyanheads/evals-mcp-server/add-prompt)<a href="https://agentmods.dev/skills/cyanheads/evals-mcp-server/add-prompt"><img src="https://agentmods.dev/badge/skills/cyanheads/evals-mcp-server/add-prompt/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/cyanheads/evals-mcp-server/add-prompt"><img src="https://agentmods.dev/badge/skills/cyanheads/evals-mcp-server/add-prompt.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 | $0.00037 | $0.01582 |
| Opus 5.5 | $0.00015 | $0.00633 |
| Sonnet 5.5 | $0.00007 | $0.00316 |
| Haiku 4.5 | $0.00004 | $0.00158 |
Grade A, and why
add-prompt 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 9d 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.
This is a copy
100% identical to add-prompt — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 144 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Context
Prompts use the prompt() builder from @cyanheads/mcp-ts-core. Each prompt lives in src/mcp-server/prompts/definitions/ with a .prompt.ts suffix. The standard registration pattern uses a definitions/index.ts barrel that collects all prompts into an allPromptDefinitions array for createApp(). Fresh scaffolds start with direct imports in src/index.ts — the barrel is introduced as definitions grow. Match the pattern already used by the project you're editing.
Prompts are pure message templates — no Context, no auth, no side effects. generate can be sync or async (returns PromptMessage[] | Promise<PromptMessage[]>).
Steps
- Gather the prompt's name, purpose, and arguments from the user's request — ask only if genuinely absent
- Create the file at
src/mcp-server/prompts/definitions/{{prompt-name}}.prompt.ts - Register the prompt in the project's existing
createApp()prompt list (directly insrc/index.tsfor fresh scaffolds, or via a barrel if the repo already has one) - Run
bun run devcheckto verify - Smoke-test with
bun run rebuild && bun run start:stdio < /dev/null— theCore services constructedlog record must list the new prompt in itspromptsfield (the message text shows only counts); if it doesn't, the prompt never reachedcreateApp()
Template
/**
* @fileoverview {{PROMPT_DESCRIPTION}}
* @module mcp-server/prompts/definitions/{{PROMPT_NAME}}
*/
import { completable, prompt, z } from '@cyanheads/mcp-ts-core';
export const {{PROMPT_EXPORT}} = prompt('{{prompt_name}}', {
description: '{{PROMPT_DESCRIPTION}}',
// title is optional — human-readable display name surfaced in prompts/list.
// title: '{{PROMPT_DISPLAY_TITLE}}',
// args is optional — omit entirely for prompts with no parameters.
// When present, all fields need .describe(). Only JSON-Schema-serializable types allowed.
// Wrap any field with completable() to enable argument autocompletion.
args: z.object({
// All fields need .describe()
// language: completable(z.string().describe('Language'), async (partial) => matchingLanguages(partial)),
}),
generate: (args) => [
{
role: 'user',
content: {
type: 'text',
text: `{{PROMPT_TEMPLATE_TEXT}}`,
},
},
],
});
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.
- 9d ago Changed · +6 lines aee181ba52ed
- 1mo ago First seen · 138 lines · 37 tokens per session scan A 270d4e2e57c9
add-prompt is a skill published in the GitHub repository cyanheads/evals-mcp-server (1 stars, last pushed 4d ago), licensed Apache-2.0. It adds 37 tokens to every session and 1,582 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to add-prompt, differing in 0 lines, and is treated as a copy.
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