Skip to main content
Glama
apetta

Vibe Math MCP

by apetta

Perpetuity Calculations

perpetuity
Read-onlyIdempotent

Calculate present value of a perpetuity for level, due, or growing payments. Solves infinite payment stream valuation for preferred stock, endowments, and rental income.

Instructions

Calculate present value of a perpetuity (infinite series of payments).

A perpetuity is an annuity that continues forever. Common in: - Preferred stock dividends - Endowment funds - Real estate with infinite rental income - UK Consol bonds (historically)

Formulas: Level Ordinary: PV = C / r Level Due: PV = C / r × (1 + r) Growing: PV = C / (r - g), where r > g

Examples:

LEVEL PERPETUITY: £1000 annual payment at 5% payment=1000, rate=0.05 Result: PV = £20,000

GROWING PERPETUITY: £1000 payment growing 3% annually at 8% discount payment=1000, rate=0.08, growth_rate=0.03 Result: PV = £20,000

PERPETUITY DUE: £1000 at period start at 5% payment=1000, rate=0.05, when='begin' Result: PV = £21,000

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
contextNoOptional annotation to label this calculation (e.g., 'Bond A PV', 'Q2 revenue'). Appears in results for easy identification.
output_modeNoOutput format: full (default), compact, minimal, value, or final. See batch_execute tool for details.full
paymentYesPeriodic payment amount (e.g., 1000)
rateYesDiscount rate per period (e.g., 0.05)
growth_rateNoPayment growth rate (None or 0 for level, e.g., 0.03 for growing)
whenNoPayment timing: 'end' or 'begin'end

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
resultYes
Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already provide readOnlyHint and idempotentHint, so the tool is clearly safe and side-effect-free. The description adds behavioral context about formulas and constraints (r > g for growing perpetuity) but does not reveal additional behavioral traits beyond what annotations convey.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is well-organized with sections for formulas, examples, and context. While it is somewhat lengthy, every sentence serves a purpose. Minor redundancy (e.g., repeating formulas in examples) could be trimmed, but overall clarity is high.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the annotations (readOnly, idempotent) and the existence of an output schema, the description adequately covers usage context, parameter semantics, and formula constraints. The examples illustrate return values, making the tool complete for its complexity.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so baseline is 3. The description enriches understanding with concrete examples (e.g., £1000 at 5% yields £20,000) and formula explanations, adding value beyond the schema descriptions alone.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool calculates present value of a perpetuity, with specific verb and resource. It provides formulas and examples but does not explicitly differentiate from sibling tools like compound_interest or financial_calcs, which also handle cash flows.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description lists common contexts (preferred stock, endowments, etc.) but does not specify when to avoid using this tool or mention alternatives. The guidance is implicit through examples but lacks explicit when-to-use versus when-not-to-use criteria.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Install Server

Other Tools

Latest Blog Posts

MCP directory API

We provide all the information about MCP servers via our MCP API.

curl -X GET 'https://glama.ai/api/mcp/v1/servers/apetta/vibe-math-mcp'

If you have feedback or need assistance with the MCP directory API, please join our Discord server