Hermes Plant — Agent Commerce Assurance

OptionLens — Black-Scholes price & Greeks

options_price

Idempotent

OptionLens (x402-paid, $0.30): deterministic Black-Scholes price and full Greeks (delta, gamma, vega, theta, rho) for European calls/puts, with dividend yield, intrinsic/time value, and moneyness.

Input Schema

TableJSON Schema

Name	Required	Description
`spot`	Yes	Underlying price (> 0)
`payer`	No	Optional wallet/account identifier; stored only as a hash
`apiKey`	No	Free-tier / plan API key (hp_free_… or a pass key). Forwarded as X-API-Key so paid tools serve from your monthly quota with NO x402 wallet. Get a free key (250 calls/mo) at https://hermesplant.com/pricing.
`strike`	Yes	Strike price (> 0)
`channel`	No	Discovery channel or source tag
`campaign`	No	Campaign tag for downstream telemetry
`xPayment`	No	Raw X-PAYMENT proof from an x402-compatible wallet/client
`actorType`	No	Caller type for analytics: agent, human, synthetic, system, or unknown
`synthetic`	No	Mark this paid retry as an internal test/probe for analytics exclusion
`optionType`	No	Option type, 'call' or 'put' (default call)
`volatility`	Yes	Annualized volatility, e.g. 0.2
`riskFreeRate`	No	Annual risk-free rate, default 0
`timeToExpiry`	Yes	Years to expiry, e.g. 0.5
`dividendYield`	No	Continuous dividend yield, default 0
`paymentSignature`	No	x402 payment proof to forward as PAYMENT-SIGNATURE and X-PAYMENT on retry
`paymentIdentifier`	No	Optional x402 payment identifier for idempotency/retry correlation

Output Schema

TableJSON Schema

Name	Required	Description
`ok`	Yes	True when the upstream storefront call returned a 2xx response
`httpStatus`	Yes	Upstream HTTP status code
`paymentRequired`	No	True when the response is an x402 HTTP 402 payment challenge

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedJul 9, 2026
- removedInput schema / additionalProperties
```
Removed value: -false
```
Changed1 schema field changedJul 9, 2026
- addedInput schema / additionalProperties
```
Added value: +false
```
First observedJul 4, 2026

TDQS

A4/5.0

Behavior4/5

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

The description discloses that the tool is x402-paid at $0.30, indicating a required payment or quota, which complements the annotations' readOnlyHint=false. It also states the computation is deterministic and lists the broad output scope, adding useful context beyond the schema.

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

Conciseness5/5

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

The description is a single, information-dense sentence that front-loads the brand and cost, then succinctly enumerates the function and outputs. No redundant words or content.

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?

The description covers the tool's core purpose, pricing model, and output breadth, while the input schema and output schema (present) handle parameter details. Given the large parameter count, the description appropriately focuses on the main function and leaves technical details to the schema.

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

Parameters3/5

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

With 100% schema description coverage, each parameter is already described. The tool description adds an overview of what the calculation includes (e.g., dividend yield) but does not elaborate on individual parameters, so the schema carries the primary semantic load.

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

Purpose5/5

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

The description clearly identifies the tool as a Black-Scholes price and Greeks calculator for European options, listing specific outputs (delta, gamma, vega, theta, rho) and inputs (dividend yield). It distinguishes itself from sibling tools like bond_analyze or cashflowlens_analyze by focusing specifically on options pricing.

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 implies usage for European option pricing but does not explicitly state when to use this tool over alternatives or when not to use it. The 'x402-paid' notation and cost hint at a monetized service, but no exclusions or alternative recommendations are provided.

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

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