Cruncher
A zero-dependency scientific calculator server that exposes 43 math operations to Claude through stdio. Built without mathjs or the official MCP SDK to stay lightweight and educational. You get basic arithmetic, trig functions (degrees and radians), logarithms, statistical analysis (mean, median, variance, standard deviation), unit conversions across 8 categories, and scientific constants from physics and chemistry. It handles the classic JavaScript floating point problem (0.1 + 0.2) with integer scaling, validates inputs with custom schema checks instead of Zod, and uses worker threads with a 3-second timeout to kill runaway factorial calculations. Three tool tiers (minimal, standard, full) let you control context window usage. Reach for this when you need Claude to crunch numbers accurately without pulling in heavy calculation libraries.
- tools
- 43
- transport
- STDIO
- env vars
- 2
- last updated
- May 8, 2026
Tools
43 toolsPublic tool metadata for what this MCP can expose to an agent.
evaluate_expressionEvaluates a plain text math expression (e.g. `(5 + 3) * 10 / 2`).
Evaluates a plain text math expression (e.g. `(5 + 3) * 10 / 2`).
No parameter schema in public metadata yet.
addAdds two numbers (a + b).
Adds two numbers (a + b).
No parameter schema in public metadata yet.
subtractSubtracts the second number from the first (a - b).
Subtracts the second number from the first (a - b).
No parameter schema in public metadata yet.
multiplyMultiplies two numbers (a * b).
Multiplies two numbers (a * b).
No parameter schema in public metadata yet.
divideDivides the first number by the second (a / b).
Divides the first number by the second (a / b).
No parameter schema in public metadata yet.
moduloCalculates the remainder (a mod b).
Calculates the remainder (a mod b).
No parameter schema in public metadata yet.
powerCalculates a raised to the power of b (a^b).
Calculates a raised to the power of b (a^b).
No parameter schema in public metadata yet.
sqrtCalculates the square root of a value.
Calculates the square root of a value.
No parameter schema in public metadata yet.
factorialCalculates the factorial of a non-negative integer (n!).
Calculates the factorial of a non-negative integer (n!).
No parameter schema in public metadata yet.
convert_unitConvert between common units. 8 categories, 80+ units.
Convert between common units. 8 categories, 80+ units.
No parameter schema in public metadata yet.
convert_baseConverts between bases 2, 8, 10, 16.
Converts between bases 2, 8, 10, 16.
No parameter schema in public metadata yet.
sineCalculates the sine of an angle.
Calculates the sine of an angle.
No parameter schema in public metadata yet.
cosineCalculates the cosine of an angle.
Calculates the cosine of an angle.
No parameter schema in public metadata yet.
tangentCalculates the tangent of an angle.
Calculates the tangent of an angle.
No parameter schema in public metadata yet.
asinCalculates the inverse sine (arcsine) of a value. Returns an angle.
Calculates the inverse sine (arcsine) of a value. Returns an angle.
No parameter schema in public metadata yet.
acosCalculates the inverse cosine (arccosine) of a value. Returns an angle.
Calculates the inverse cosine (arccosine) of a value. Returns an angle.
No parameter schema in public metadata yet.
atanCalculates the inverse tangent (arctangent) of a value. Returns an angle.
Calculates the inverse tangent (arctangent) of a value. Returns an angle.
No parameter schema in public metadata yet.
logarithmCalculates the base-10 logarithm of a value.
Calculates the base-10 logarithm of a value.
No parameter schema in public metadata yet.
natural_logCalculates the natural logarithm (base-e) of a value.
Calculates the natural logarithm (base-e) of a value.
No parameter schema in public metadata yet.
sumCalculates the sum of an array of numbers.
Calculates the sum of an array of numbers.
No parameter schema in public metadata yet.
avgCalculates the average of an array of numbers.
Calculates the average of an array of numbers.
No parameter schema in public metadata yet.
medianCalculates the median of an array of numbers.
Calculates the median of an array of numbers.
No parameter schema in public metadata yet.
minFinds the minimum value in an array of numbers.
Finds the minimum value in an array of numbers.
No parameter schema in public metadata yet.
maxFinds the maximum value in an array of numbers.
Finds the maximum value in an array of numbers.
No parameter schema in public metadata yet.
countCounts the number of elements in an array.
Counts the number of elements in an array.
No parameter schema in public metadata yet.
rangeCalculates the range (max - min) of an array.
Calculates the range (max - min) of an array.
No parameter schema in public metadata yet.
percentileCalculates the value at a given percentile (0-100).
Calculates the value at a given percentile (0-100).
No parameter schema in public metadata yet.
varianceVariance of an array. Sample (n-1) or population (n).
Variance of an array. Sample (n-1) or population (n).
No parameter schema in public metadata yet.
std_devStandard deviation. Sample (n-1) or population (n).
Standard deviation. Sample (n-1) or population (n).
No parameter schema in public metadata yet.
percentage_ofWhat is X% of Y? e.g., 15% of 200 = 30.
What is X% of Y? e.g., 15% of 200 = 30.
No parameter schema in public metadata yet.
percentage_change% change from A to B. e.g., 50→80 = 60%.
% change from A to B. e.g., 50→80 = 60%.
No parameter schema in public metadata yet.
percentage_reverseX is Y% of what? e.g., 30 is 15% of 200.
X is Y% of what? e.g., 30 is 15% of 200.
No parameter schema in public metadata yet.
absoluteCalculates the absolute value of a number.
Calculates the absolute value of a number.
No parameter schema in public metadata yet.
get_constantReturns the value of a mathematical, physical, or chemical constant.
Returns the value of a mathematical, physical, or chemical constant.
No parameter schema in public metadata yet.
memory_clearClears the calculator memory (MC).
Clears the calculator memory (MC).
No parameter schema in public metadata yet.
memory_recallRecalls the value stored in memory (MR).
Recalls the value stored in memory (MR).
No parameter schema in public metadata yet.
memory_addAdds a value to the current memory (M+).
Adds a value to the current memory (M+).
No parameter schema in public metadata yet.
memory_subtractSubtracts a value from the current memory (M-).
Subtracts a value from the current memory (M-).
No parameter schema in public metadata yet.
set_angle_modeSet global angle mode (default: degrees).
Set global angle mode (default: degrees).
No parameter schema in public metadata yet.
get_angle_modeGet current angle mode.
Get current angle mode.
No parameter schema in public metadata yet.
batchExecute multiple tool calls sequentially.
Execute multiple tool calls sequentially.
No parameter schema in public metadata yet.
cache_clearClear computation cache.
Clear computation cache.
No parameter schema in public metadata yet.
cache_infoShow cache stats.
Show cache stats.
No parameter schema in public metadata yet.
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CRUNCHER_TOOL_SETTool exposure tier: 'minimal' (5 tools), 'standard' (34 tools, default), or 'full' (43 tools)
CRUNCHER_TIMEOUTWorker thread timeout in milliseconds for heavy calculations (default: 3000, range: 100-60000)
Readme
Cruncher: The Scientific Calculator MCP Server
A powerful scientific calculator for your AI assistant, built as a Model Context Protocol (MCP) server. Cruncher allows compatible AI clients (like Claude Desktop) to perform complex mathematical calculations, handle memory, perform statistical analysis, and access scientific constants with a simple, secure, and standardized interface.
🌟 The Purity Promise (Zero Dependencies)
Details
- Repository
- github.com/islobodan/cruncher-mcp
- Website
- github.com/islobodan/cruncher-mcp#readme
- Package
@slbdn/cruncher-mcp- Transport
- STDIO
- Registry
- MCP registry, active