A transparent, 100% deterministic what-if & scenario simulation engine for AI agents. Hand it assumptions — growth, churn, pricing, costs, a time horizon — and get back projected outcomes over time, sensitivity analysis, and break-even solving, each with a plain-language explanation.
Live endpoint:
https://scenariosim-mcp.pages.dev/mcp
● live · free tier: 20 calls/day, no key required
Identical inputs always yield byte-identical output. Every number runs through 40-digit decimal math — never floats, never drift over 100 periods.
Every result echoes back the exact assumptions used (defaults filled in), the methodology, per-period projections, and a natural-language explanation.
No database, no sessions, no hidden state. Pure functions over your assumptions. Trivial to host and reason about.
One consistent JSON envelope for success and error. Errors are structured and actionable — never raw exceptions.
Not just a projection: sweep any input to see what moves the outcome, or solve for the value that hits your target.
SaaS growth, pricing, churn, cost cuts, hiring, runway, unit economics, funnels — or bring your own metrics.
| Tool | Purpose |
|---|---|
run_scenario | Main tool: project a template or free-form model over time → projections, key_results, assumptions, explanation. |
sensitivity_analysis | Vary one or more inputs and show the impact on a target metric, with elasticity + influence ranking. |
break_even | Solve for the input value required to reach a target metric value (bisection). |
compare_scenarios | Run 2–3 scenarios side by side with deltas and an optional winner. |
list_templates | Discovery: every template with inputs, defaults, and available outputs. |
health_check | Version, status, and capabilities. |
saas_growthpricing_changechurn_impact cost_reductionhiring_plancash_runway unit_economicsmarketing_funnelcompound_growth custom
~/.cursor/mcp.json
{
"mcpServers": {
"scenariosim": {
"url": "https://scenariosim-mcp.pages.dev/mcp"
}
}
}claude_desktop_config.json — via mcp-remote bridge
{
"mcpServers": {
"scenariosim": {
"command": "npx",
"args": ["-y", "mcp-remote", "https://scenariosim-mcp.pages.dev/mcp"]
}
}
}.vscode/mcp.json
{
"servers": {
"scenariosim": {
"type": "http",
"url": "https://scenariosim-mcp.pages.dev/mcp"
}
}
}curl -s https://scenariosim-mcp.pages.dev/mcp \
-H 'content-type: application/json' \
-H 'accept: application/json, text/event-stream' \
-d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{
"name":"run_scenario","arguments":{
"template":"saas_growth",
"inputs":{"starting_customers":200,"new_customers_per_period":40,
"churn_rate":0.03,"arpu":60},
"horizon":12}}}'{
"status": "success",
"scenario": "saas_growth",
"period_label": "month",
"horizon": 12,
"key_results": {
"ending_customers": 449.7,
"ending_mrr": 26982.1,
"ending_arr": 323785.2,
"total_churned_customers": 82.4,
"cumulative_revenue": 232104.6
},
"projections": [
{ "period": 0, "customers": 200, "mrr": 12000 },
{ "period": 1, "customers": 234, "mrr": 14040, "new_customers": 40, "churned_customers": 6 }
],
"assumptions_used": { "template": "saas_growth", "churn_rate": "0.03", "arpu": "60", "horizon": 12 },
"methodology": { "model": "SaaS Growth", "deterministic": true, "precision": "decimal.js (40 significant digits)" },
"explanation": "Starting from 200 customers and adding 40 per month (churn 3%), after 12 months you reach ..."
}Headline numbers are rounded for readability; every key result also carries a full-precision value_exact string so no precision is lost.
Start free to evaluate. When your agent needs real volume,
upgrade in two clicks — pay by card, get an API key instantly, and send it as
X-API-Key. Every plan has all six tools and all templates. Cancel anytime.
$0
For evaluation & low-volume testing.
$12/mo
Best for a single production agent.
$39/mo
For fleets & high-volume workloads.
Secure checkout by Stripe · cards & wallets · promo codes supported · manage anytime at the billing portal. Prices in USD.
{
"mcpServers": {
"scenariosim": {
"url": "https://scenariosim-mcp.pages.dev/mcp",
"headers": { "X-API-Key": "ssim_live_your_key_here" }
}
}
}Prefer to self-host? The engine is open-source (MIT) and fully stateless — run your own copy on Cloudflare Pages (or any Node/Deno/Bun runtime) with unlimited calls and no keys.