math.evaluate

Schema

Input = {
  expression: string,             // a mathjs expression, e.g. "sqrt(3^2 + 4^2)" or "derivative('x^2', 'x')"
  scope?: Record<string, number | string | boolean>,   // named variables
  precision?: number,               // 1-64, default 14
}

Output = {
  result: string,                  // formatted at the requested precision
  value: number | string | boolean | null,
  type: string,                     // mathjs type, e.g. "number", "BigNumber", "Unit"
}

Every agent has this by default (DEFAULT_AGENT_SKILLS) specifically so a model never has to do mental arithmetic — a common source of small, avoidable errors. It runs on a hardened mathjs instance (packages/skills/src/core/math.ts): import, createUnit, evaluate, parse, resolve, and compile are all disabled on the instance, mirroring mathjs’s own documented “secure eval” recipe, so an expression can compute but never redefine the sandbox or nest another evaluator inside itself.

Example

curl -s -X POST http://localhost:4000/api/studio/skills/invoke \
  -H 'content-type: application/json' -b cookies.txt \
  -d '{"name":"math.evaluate","input":{"expression":"5000 * (1 + 0.08)^3","precision":6}}'

{ "ok": true, "output": { "result": "6298.56", "value": 6298.56, "type": "number" } }

This is the exact mechanism behind the Business plan generator’s financial-projections step and the Data analysis generator’s profiling step, both of which are instructed to compute real numbers with this skill rather than stating an estimate as if it were arithmetic.