The Clearing — The Lantern & Consensual Agent Lab

decode_readonly_evm_calldata

Decode 4-byte EVM calldata selectors and determine read-only vs. state-mutating posture.

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": {
      "calldata_hex": "<calldata_hex>"
    },
    "name": "decode_readonly_evm_calldata"
  }
}

Input Schema

Name	Required	Description	Default
`calldata_hex`	Yes	Hex calldata starting with 0x (e.g. 0x70a08231...).

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 14, 2026

TDQS

A3.8/5.0

Behavior3/5

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

With no annotations, the description carries the full burden, and it does disclose a real behavioral trait beyond the name: the output classifies read-only versus state-mutating posture. However, it says nothing about how unknown or non-matching 4-byte selectors are handled, whether decoding returns a signature/name or only a boolean classification, or whether it performs any network lookup.

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?

A single front-loaded sentence with no filler, and the primary action precedes the secondary outcome. Minor imprecision: 'decode 4-byte selectors' conflates the 4-byte selector with the full calldata payload the parameter actually accepts.

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

Completeness5/5

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

The tool has one fully documented parameter, no annotations, and no nested structures; the description covers both what it does and the key output trait an agent would care about (mutability posture). Given this low complexity, nothing essential 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 coverage is 100% with a single required parameter, and the schema description already states the 0x-prefixed hex format with an example. The tool description adds no further detail about length constraints, malformed input behavior, or whether calldata beyond the selector is used.

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 names a specific verb ('Decode') and resource ('4-byte EVM calldata selectors') and adds the secondary outcome ('read-only vs. state-mutating posture'). No sibling tool in the catalog operates in the EVM domain, so no differentiation is needed for an agent to identify it.

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?

Usage is only implied by the domain framing — an agent infers it applies when it has EVM calldata that needs interpretation. There is no explicit when-to-use, when-not-to-use, prerequisite, or alternative named (e.g., what to do for full ABI decoding versus bare selector lookup).

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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