diff --git a/legacy/package.json b/legacy/package.json
index d2d2e849..8bda68f6 100644
--- a/legacy/package.json
+++ b/legacy/package.json
@@ -43,6 +43,7 @@
     "@inquirer/editor": "^1.2.0",
     "@inquirer/select": "^1.2.1",
     "debug": "^4.3.4",
+    "expr-eval": "^2.0.2",
     "handlebars": "^4.7.7",
     "js-tiktoken": "^1.0.6",
     "jsonrepair": "^3.1.0",
diff --git a/legacy/pnpm-lock.yaml b/legacy/pnpm-lock.yaml
index 32511920..2d8dd621 100644
--- a/legacy/pnpm-lock.yaml
+++ b/legacy/pnpm-lock.yaml
@@ -20,6 +20,9 @@ dependencies:
   debug:
     specifier: ^4.3.4
     version: 4.3.4
+  expr-eval:
+    specifier: ^2.0.2
+    version: 2.0.2
   handlebars:
     specifier: ^4.7.7
     version: 4.7.7
@@ -1793,6 +1796,10 @@ packages:
     engines: {node: '>=12.0.0'}
     dev: true
 
+  /expr-eval@2.0.2:
+    resolution: {integrity: sha512-4EMSHGOPSwAfBiibw3ndnP0AvjDWLsMvGOvWEZ2F96IGk0bIVdjQisOHxReSkE13mHcfbuCiXw+G4y0zv6N8Eg==}
+    dev: false
+
   /external-editor@3.1.0:
     resolution: {integrity: sha512-hMQ4CX1p1izmuLYyZqLMO/qGNw10wSv9QDCPfzXfyFrOaCSSoRfqE1Kf1s5an66J5JZC62NewG+mK49jOCtQew==}
     engines: {node: '>=4'}
diff --git a/legacy/src/tools/calculator.ts b/legacy/src/tools/calculator.ts
new file mode 100644
index 00000000..7dbe2c66
--- /dev/null
+++ b/legacy/src/tools/calculator.ts
@@ -0,0 +1,46 @@
+import { Parser } from 'expr-eval'
+import { z } from 'zod'
+
+import * as types from '@/types'
+import { BaseTask } from '@/task'
+
+export const CalculatorInputSchema = z.string().describe('expression')
+export const CalculatorOutputSchema = z
+  .number()
+  .describe('result of calculating the expression')
+
+export type CalculatorInput = z.infer<typeof CalculatorInputSchema>
+
+export type CalculatorOutput = z.infer<typeof CalculatorOutputSchema>
+
+export class CalculatorTool extends BaseTask<
+  CalculatorInput,
+  CalculatorOutput
+> {
+  constructor(opts: types.BaseTaskOptions) {
+    super(opts)
+  }
+
+  public override get inputSchema() {
+    return CalculatorInputSchema
+  }
+
+  public override get outputSchema() {
+    return CalculatorOutputSchema
+  }
+
+  public override get name(): string {
+    return 'calculator'
+  }
+
+  public get descriptionForModel(): string {
+    return 'Useful for getting the result of a math expression. The input to this tool should be a valid mathematical expression that could be executed by a simple calculator.'
+  }
+
+  protected override async _call(
+    ctx: types.TaskCallContext<CalculatorInput>
+  ): Promise<CalculatorOutput> {
+    const result = Parser.evaluate(ctx.input!)
+    return result
+  }
+}
diff --git a/legacy/test/calculator.test.ts b/legacy/test/calculator.test.ts
new file mode 100644
index 00000000..f16f39f6
--- /dev/null
+++ b/legacy/test/calculator.test.ts
@@ -0,0 +1,28 @@
+import test from 'ava'
+import { expectTypeOf } from 'expect-type'
+
+import { CalculatorTool } from '@/tools/calculator'
+
+import { createTestAgenticRuntime } from './_utils'
+
+test('CalculatorTool', async (t) => {
+  const agentic = createTestAgenticRuntime()
+  const tool = new CalculatorTool({ agentic })
+
+  const res = await tool.call('1 + 1')
+  t.is(res, 2)
+  expectTypeOf(res).toMatchTypeOf<number>()
+
+  const res2 = await tool.callWithMetadata('cos(0)')
+  t.is(res2.result, 1)
+  expectTypeOf(res2.result).toMatchTypeOf<number>()
+
+  const { taskId, ...metadata } = res2.metadata
+  t.true(typeof taskId === 'string')
+  t.deepEqual(metadata, {
+    success: true,
+    taskName: 'calculator',
+    numRetries: 0,
+    error: undefined
+  })
+})