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 elevanaltd/HestAI-MCP --skill vercel-previewgit clone --depth 1 https://github.com/elevanaltd/HestAI-MCPWrote 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/elevanaltd/hestai-mcp/vercel-preview)<a href="https://agentmods.dev/skills/elevanaltd/hestai-mcp/vercel-preview"><img src="https://agentmods.dev/badge/skills/elevanaltd/hestai-mcp/vercel-preview/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/elevanaltd/hestai-mcp/vercel-preview"><img src="https://agentmods.dev/badge/skills/elevanaltd/hestai-mcp/vercel-preview.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 | $0.00022 | $0.01398 |
| Opus 5.5 | $0.00009 | $0.00559 |
| Sonnet 5.5 | $0.00004 | $0.00280 |
| Haiku 4.5 | $0.00002 | $0.00140 |
Grade A, and why
vercel-preview scanned grade A with 1 finding 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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
curl -I -H "x-vercel-protection-bypass: $VERCEL_AUTOMATION_BYPASS_SECRET" \ How it starts
The opening of the file, as written. The whole thing — 198 lines — stays where its author put it; the contents beside it link to each section on GitHub.
===VERCEL_PREVIEW=== META: TYPE::SKILL VERSION::1.0 STATUS::ACTIVE COMPRESSION_TIER::AGGRESSIVE DOMAIN::HEPHAESTUS[tool_crafting]⊕HERMES[automation]
§1::PURPOSE
Enable automated access to Vercel protected preview deployments for CI/CD, UI validation, and E2E testing
§2::PROTECTION_BYPASS_PATTERN
METHOD::Protection_Bypass_for_Automation
SECRET_NAME::VERCEL_AUTOMATION_BYPASS_SECRET
SECRET_LOCATIONS::[
vercel_dashboard::"Project Settings -> Deployment Protection -> Auto-injected",
github_secrets::"Repository Settings -> Secrets -> Actions",
local_dev::".env.local[GITIGNORED]"
]
ACCESS_METHODS::[
HTTP_HEADER::"x-vercel-protection-bypass: ${VERCEL_AUTOMATION_BYPASS_SECRET}",
QUERY_PARAM::"?x-vercel-protection-bypass=${VERCEL_AUTOMATION_BYPASS_SECRET}"
]
§3::CI_WORKFLOW_INTEGRATION
§4::GITHUB_ACTIONS_PATTERN
# .github/workflows/ci.yml
jobs:
integration-tests:
runs-on: ubuntu-latest
steps:
- name: Wait for Vercel Preview
uses: patrickedqvist/[email protected]
id: vercel
with:
token: ${{ secrets.GITHUB_TOKEN }}
max_timeout: 300
- name: Run E2E Tests
env:
VERCEL_PREVIEW_URL: ${{ steps.vercel.outputs.url }}
VERCEL_AUTOMATION_BYPASS_SECRET: ${{ secrets.VERCEL_AUTOMATION_BYPASS_SECRET }}
run: npm run test:e2e
§5::PLAYWRIGHT_CONFIGURATION
// playwright.config.ts
import { defineConfig } from '@playwright/test';
export default defineConfig({
use: {
baseURL: process.env.VERCEL_PREVIEW_URL,
extraHTTPHeaders: {
'x-vercel-protection-bypass': process.env.VERCEL_AUTOMATION_BYPASS_SECRET || '',
},
},
});
§6::CHROME_DEVTOOLS_MCP_ACCESS
CHROME_DEVTOOLS_PATTERN::[
// Navigate with bypass query param
mcp__chrome-devtools__navigate_page(
url: "${VERCEL_PREVIEW_URL}?x-vercel-protection-bypass=${SECRET}"
),
// OR set header via evaluate_script before navigation
mcp__chrome-devtools__evaluate_script(
function: "() => { /* custom fetch with header */ }"
)
]
§7::SETUP_CHECKLIST
PREREQUISITES::[
1::vercel_pro_plan_or_higher[automation_bypass_is_paid_feature],
2::deployment_protection_enabled[Project_Settings->Deployment_Protection],
3::automation_bypass_generated[generates_VERCEL_AUTOMATION_BYPASS_SECRET]
]
CONFIGURATION::[
1::add_to_github_secrets[repository_settings->secrets->actions],
2::add_to_local_env[.env.local_for_local_testing],
3::update_ci_workflow[pass_secret_to_test_steps],
4::configure_playwright[extraHTTPHeaders_or_query_param],
5::verify_access[curl_with_header_returns_200]
]
VERIFICATION_COMMAND::
curl -I -H "x-vercel-protection-bypass: $VERCEL_AUTOMATION_BYPASS_SECRET" \
https://your-preview-url.vercel.app
# Should return 200, not 401/403
§8::SECURITY_CONSIDERATIONS
NEVER::[
commit_secret_to_git,
log_secret_in_CI_output,
share_secret_in_documentation,
use_secret_in_client_side_code
]
ALWAYS::[
use_github_secrets_for_CI,
use_gitignored_.env.local_for_local,
rotate_if_exposed,
limit_to_preview_deployments[not_production]
]
ROTATION::[
location::"Vercel Dashboard -> Project -> Settings -> Deployment Protection",
action::"Regenerate secret",
update::"GitHub Secrets + local .env.local"
]
§9::TROUBLESHOOTING
ISSUE::401_Unauthorized_despite_bypass[
CHECK::[
secret_correct_and_not_stale,
header_name_exact["x-vercel-protection-bypass"],
secret_passed_to_env_in_CI,
not_trying_production_URL[bypass_for_previews_only]
]
]
ISSUE::Preview_not_found[
CHECK::[
PR_created_and_pushed,
vercel_integration_enabled,
wait_for_deployment_complete[use_wait-for-vercel-preview_action]
]
]
ISSUE::Bypass_not_available[
CHECK::[
vercel_plan[Pro_or_higher_required],
deployment_protection_enabled_first,
feature_may_require_team_admin
]
]
§10::AGENT_INTEGRATION
UI_VALIDATOR_USAGE::[
RECEIVES::[preview_url, acceptance_criteria],
ACCESSES::preview_via_bypass_header,
VALIDATES::visual+functional_requirements,
RETURNS::PASS/FAIL+evidence
]
CI_PIPELINE_USAGE::[
TIER_1::quality_gates[no_preview_needed],
TIER_2::preview_integration[uses_bypass_for_E2E],
PATTERN::wait_for_preview->export_url->run_tests_with_bypass
]
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 First seen · 198 lines · 22 tokens per session scan A 29292fd3e690
vercel-preview is a skill published in the GitHub repository elevanaltd/HestAI-MCP (0 stars, last pushed 11d ago), licensed Apache-2.0. It adds 22 tokens to every session and 1,398 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
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