ScorpTech x402 API

Fourth Sum

fourth_sum

Read-onlyIdempotent

The sum of the first n fourth powers, n(n+1)(2n+1)(3n^2+3n-1)/30. The sum through 0 is 0, through 1 is 1, and through 10 is 25333. n runs from 0 to 10000. Past 15 digits the value is a decimal string. Price: $0.001 USDC per successful call (x402, Solana). Same tool over HTTPS: POST https://scorptech.it.com/api/x402/v1/fourth-sum

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "n": "<n>"
    },
    "name": "fourth_sum"
  }
}

Input Schema

Name	Required	Description	Default
`n`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

AddedOct 23, 2026

TDQS

A3.7/5.0

Behavior4/5

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds genuinely new behavioral facts: the payment requirement ($0.001 USDC per successful call via x402 on Solana) and the output-format edge case (past 15 digits the value is returned as a decimal string). That is meaningful context beyond the annotations.

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 front-loads the formula and then packs examples, range, output-format behavior, pricing, and an alternate endpoint into tight sentences. It is dense but every sentence carries useful information; no fluff or repetition.

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?

There is no output schema, but the description flags the important return-value quirk (decimal string beyond 15 digits) along with payment terms and range. For a single-parameter pure computation tool this covers what an agent needs; only explicit sibling routing guidance is missing.

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?

Schema description coverage is 0%, so the description must carry the load for the single parameter n. It does state that n runs from 0 to 10000, but that range is already encoded in the schema's minimum/maximum; the semantic meaning of n as the number of terms is only implied by the formula. Adequate but not compensating fully for the missing schema description.

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 states a specific computation ('sum of the first n fourth powers') and even supplies the closed-form formula, making the tool's job unambiguous. It does not explicitly contrast with siblings like fifth_sum or cube_sum, but the name and formula make the distinction self-evident.

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 gives the valid domain of n (0 to 10000) but never says when to choose this tool over related sum tools such as fifth_sum or cube_sum, nor when not to use it. Usage is implied by the range constraint rather than stated.

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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