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by io.github.zvmzaretsky
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Keyless pre-sign transaction simulation (paid $0.02)

simulate

PAID $0.02 (x402, USDC on Base). Keyless pre-sign analysis of {chain, from?, to, data, value?}: public-RPC eth_call revert check + static calldata decode predicting approval/transfer deltas + risk flags (unlimited approval, approval-for-all, reverts). Honest keyless limitation stated in the response (no full fork trace). Without payment returns the x402 challenge; pass x_payment. Free teaser: simulate_free.

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": {
      "chain": "<chain>",
      "to": "<to>"
    },
    "name": "simulate"
  }
}

Input Schema

NameRequiredDescriptionDefault
toYes0x target contract/recipient.
dataNo0x calldata (omit for a plain value transfer).
fromNo0x sender (optional but improves accuracy).
chainYesChain: ethereum | base | bsc | polygon | arbitrum | optimism.
valueNoValue in wei (optional).
x_paymentNox402 payment payload (base64) for this PAID tool. If supplied it is forwarded as the X-PAYMENT header to settle the call and return the real result instead of a 402 challenge. Omit to get the price challenge first.

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observed

TDQS

A4.3/5.0
Behavior5/5

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

With no annotations, the description fully discloses behavioral traits: it is paid, keyless (with the limitation 'no full fork trace'), uses public RPC, performs static decode, flags risks, and returns a 402 challenge without payment. This is highly transparent.

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 moderately sized but extraordinarily dense, covering cost, function, limitations, payment flow, and free alternative in about four sentences. It could be better structured with bullets, but every sentence earns its place.

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 tool's complexity (paid, with payment flow and keyless limitation) and lack of output schema/annotations, the description covers the critical points: payment behavior, what the tool checks, and its limitation. It omits error handling or rate limits, but those are not essential for basic selection and invocation.

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 coverage is 100% with descriptions for all 6 parameters. The description lists the parameter set ({chain, from?, to, data, value?}) and mentions x_payment, but generally repeats schema information without adding new meaning beyond the overall purpose.

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 states the tool's function: 'Keyless pre-sign analysis' with revert check, calldata decode, and risk flags. It also distinguishes itself from the sibling tool simulate_free by pointing to it as a free teaser, clarifying the paid nature.

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

Usage Guidelines4/5

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

The description provides practical usage guidance: it tells users that without payment they get an x402 challenge, and to pass x_payment for real results. It also mentions simulate_free for a free alternative, though it does not explicitly exclude other sibling tools for different use cases.

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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