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Expression Evaluator – Variable Inspector
x402
Expression Evaluator – Variable Inspector is a paid API for AI agents from math.openverbs.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-14).
Inspects a mathematical or logical expression and extracts the variables contained within it
Price / call$0.004
Success—
StatusUnknown
How this service works
Parse an expression and return the free variables it references, without evaluating it — so an agent can discover which inputs a formula needs before supplying values. A syntax error is a clean 400.
Output
A structured response listing all variable names (identifiers) found within the provided expression string, allowing the caller to know exactly which unknowns or parameters the expression depends on.
Example use cases
Formula dependency analysis
“I have the formula 'a*sin(b*t + c) + d' — can you tell me all the variables it depends on so I know what inputs I need to evaluate it?”
Equation variable extraction for solver setup
“Before I run my equation solver, can you parse 'alpha * x^2 + beta * x + gamma = 0' and list out all the variable names it contains?”
Checking expression inputs before evaluation
“I want to make sure I know every variable in this expression before plugging in values: '(p * q) / (r + s * t)' — what variables does it use?”
Technical details
Endpoint
POSThttps://math.openverbs.com/v1/variablesWhen to prefer
Use this endpoint when you need to programmatically determine which variables or identifiers are present in a mathematical or logical expression before evaluating it, building a solver, or validating inputs. It is particularly useful in dynamic formula engines, educational tools, or symbolic math pipelines where expressions are user-supplied and the required variable bindings are unknown ahead of time.
Side effects
- Expression string is empty or missing — returns validation error
- Expression exceeds 1000 character limit — rejected with schema error
- Malformed or unparseable expression — may return parse error or empty variable list
- Network or service unavailability — HTTP 5xx error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object |
Tags
x402
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