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Reported issues for calculator-mcp-server

Pod holds 15 of 15 GitHub reports that passed its relevance review. This can include external user reports, maintainer-confirmed bugs, and concrete feature gaps. Treat them as evidence to inspect, not a count of distinct defects.

Back to calculator-mcp-server.

Most discussed

bug(calculate): a function used as a value gets a unit-mismatch recovery hint (5 min to s)

Server version

0.4.3

mcp-ts-core version

^0.13.6

Runtime

Bun

Runtime version

Bun 1.4.0 (via runToolContract)

Transport

stdio

Description

When implicit multiplication puts a function next to a value, math.js throws a type error from multiplyScalar. The call fails with type_mismatch, and the recovery tells the caller to attach or strip units. That points the wrong way. 5 min to s reads min as the minimum function, not minutes. (f(x) = x^2)(3)…

Read the thread · 2026-09-24 · closed · 1 comment

bug(calculate): custom units (knot, lightyear) hijack unit simplification of SI results

Server version

0.4.3

mcp-ts-core version

^0.13.6

Runtime

Bun

Runtime version

Bun 1.4.0 (via runToolContract)

Transport

stdio

Description

The custom units the server registers (mph, knot, lightyear) take over math.js's automatic unit simplification. A velocity computed from SI units comes back in knots, and a product involving a length can come back in light-years. The values are numerically right but unreadable, and they aren't in the units the caller…

Read the thread · 2026-09-24 · closed · 1 comment

bug(calculate): Fraction mode rejects whole-number dimension arguments with fraction_unsupported

Server version

0.4.3

mcp-ts-core version

^0.13.6

Runtime

Bun

Runtime version

Bun 1.4.0 (via runToolContract)

Transport

stdio

Description

Under numericType: "Fraction", the dimension argument of matrix reductions and concat parses as a Fraction, and those functions accept only a number there. The call fails with fraction_unsupported, whose message says the result has no exact rational value or the function can't be computed in Fraction mode. Both are…

Read the thread · 2026-09-24 · closed · 1 comment

bug(calculate): Fraction mode returns inexact floats without error and rejects integer indexes

Server version

0.4.3

mcp-ts-core version

^0.13.6

Runtime

Bun

Runtime version

Bun 1.4.0 (via runToolContract)

Transport

stdio

Description

Under numericType: "Fraction", constants and non-integer powers fall back to a 64-bit float, and the call succeeds with resultType number. The caller asked for exact arithmetic and gets a rounded value with no error, which is the case fraction_unsupported exists to flag. Separately, integer indexes parse as Fractions,…

Read the thread · 2026-09-24 · closed · 1 comment

bug(calculate): assignments in an expression leak into scopeVars

Server version

0.4.3

mcp-ts-core version

^0.13.6

Runtime

Bun

Runtime version

Bun 1.4.0 (via runToolContract)

Transport

stdio

Description

evaluate passes the caller's scope object to math.js, and an assignment inside the expression writes into that object. The handler builds scopeVars from Object.keys(scope) after evaluation, so the output lists names the caller never sent.

Related: #12 (scopeVars echo).

Steps to reproduce

  1. calculate with…

Read the thread · 2026-09-24 · closed · 1 comment

bug(calculate): Fraction mode misreports matrix size arguments and exponent literals

Server version

0.4.3

mcp-ts-core version

^0.13.6

Runtime

Bun

Runtime version

Bun 1.4.0 (via runToolContract)

Transport

stdio

Description

Under numericType: "Fraction", two failures carry messages that point the caller the wrong way. Size arguments to matrix constructors parse as Fractions, and those functions have no Fraction signature, so zeros(2) fails with fraction_unsupported, whose message blames an irrational result. Exponent literals are…

Read the thread · 2026-09-24 · closed · 1 comment

bug(calculate): multiple-expression scan ignores single-quoted strings

Server version

0.4.3

mcp-ts-core version

^0.13.6

Runtime

Node.js

Runtime version

Bun 1.4.0 (via the tool handler)

Transport

stdio

Description

hasExpressionSeparator() (#16) treats only " as a string delimiter; its comment says ' is only the transpose operator. math.js 15 also parses '…' as a string literal ('a;b' → "a;b"). A ; or newline inside a single-quoted string is therefore rejected as multiple_expressions. A " or…

Read the thread · 2026-09-24 · closed · 1 comment

bug(calculate): help() in an expression escapes the typed-error mapping as an internal error

Server version

0.4.3

mcp-ts-core version

^0.13.6

Runtime

Node.js

Runtime version

Bun 1.4.0 (via runToolContract)

Transport

stdio

Description

Calling math.js help inside an expression fails with an uncontracted internal error. help is not in DISABLED_FUNCTIONS, so it returns a Help object that passes validateResultType; inst.format(raw) then renders the object's examples by calling the…

Read the thread · 2026-09-24 · closed · 1 comment

Most recent

bug(calculate): evaluation-time math.js errors (unit/type mismatch, domain, dimension) surface as parse_failed with a syntax hint

Server version

0.4.1

mcp-ts-core version

^0.12.3

Runtime

Bun

Runtime version

Bun 1.3.x

Transport

HTTP (Streamable HTTP)

Description

MathService.runWithTimeout maps every non-timeout error to parse_failed (#19 carved out only Fraction conversion), with a recovery about balanced parentheses and function names. Most of those errors come from math.js evaluating an expression that already parsed — argument types, unit mismatches, arity,…

Read the thread · 2026-08-22 · closed · 1 comment

feat(config): default MCP_SESSION_MODE to stateless across env, Docker, and src

Dockerfile sets ENV MCP_SESSION_MODE="stateless", but .env.example carries a commented # MCP_SESSION_MODE=stateful, whose comment documents the value set as stateful | stateless (default: stateful). The container and the same code run via bunx, npm start, or from source therefore resolve to different session modes — stateless in Docker, stateful everywhere else, since the framework schema defaults to auto and auto resolves to stateful.

The hosted deployment runs stateless…

Read the thread · 2026-08-22 · closed · 1 comment

bug(calculate): evaluate()/simplify()/derivative() inside an expression misdirect instead of pointing at the operation parameter

Server version

0.4.0

mcp-ts-core version

0.10.10

Runtime

Bun

Runtime version

Bun 1.3.x (hosted Docker image)

Transport

HTTP (Streamable HTTP)

OS

Linux (Docker)

Description

All three operation values — evaluate, simplify, derivative — are also blocked function names inside expressions (#18). A caller who writes the operation as a function call is misdirected:

Read the thread · 2026-08-21 · closed · 1 comment

bug(calculate): format() renders expression, result, and scope-key text as live Markdown

Server version

0.4.0

mcp-ts-core version

^0.10.10

Runtime

Node.js

Runtime version

Node v26.5.0

Transport

HTTP (Streamable HTTP)

Description

calculate's format() interpolates caller-controlled text into content[] Markdown as-is: the expression in a fixed single-backtick span, the result and scope-variable names as raw text. String, string-matrix, and object results render as links and HTML, a backtick closes the expression span early, and a multi-line…

Read the thread · 2026-08-11 · closed · 1 comment

bug(calculate): number-mode config stub breaks eigs, schur, intersect and skews tolerance comparisons

Server version

0.4.0

mcp-ts-core version

^0.10.10

Runtime

Node.js

Runtime version

Node v26.5.0

Transport

HTTP (Streamable HTTP)

Description

eigs, advertised in calculator://help, fails for valid matrices in default number mode, and the same cause breaks or skews other functions. The hardened number instance replaces config with a throwing stub that carries none of math.js's config properties. math.js injects config into each factory when it is…

Read the thread · 2026-08-11 · closed · 1 comment

bug(calculate): notation aliases rewrite quoted string literals

Server version

0.4.0

mcp-ts-core version

^0.10.10

Runtime

Node.js

Runtime version

Node v26.5.0

Transport

HTTP (Streamable HTTP)

Description

calculate rewrites standard-notation aliases inside quoted string literals. normalizeNotation() (#13) applies NOTATION_ALIAS_PATTERN to the raw expression, so ln( or an arc*( name inside a string changes before math.js parses it. Double- and single-quoted strings (math.js 15 accepts both) are affected, under…

Read the thread · 2026-08-11 · closed · 1 comment

bug(calculate): non-finite BigNumber, Unit, and object results bypass undefined_result

Server version

0.4.0

mcp-ts-core version

^0.10.10

Runtime

Node.js

Runtime version

Node v26.3.1

Transport

HTTP (Streamable HTTP)

Description

calculate rejects non-finite results with undefined_result, but containsNonFinite() in src/services/math/math-service.ts only recognizes JS numbers, arrays, Complex (re/im), and matrices (toArray()). A non-finite value held in a BigNumber (scalar or matrix element), a Unit, or a plain object passes the…

Read the thread · 2026-07-02 · closed · 1 comment

The remaining reports are on the project's issue tracker.