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Glama

FabTally Decode

by io.github.zvmzaretsky

Fetch a contract's verified ABI + proxy resolution (paid $0.002)

abi_fetch

PAID $0.002 (x402, USDC on Base). Fetch the verified ABI + metadata for a contract. Give {address, chain}; get the ABI JSON, verification status/source (Sourcify or Blockscout), the callable function/event signatures, and full proxy-implementation resolution (EIP-1967/1822/OZ-legacy/beacon) — returning the implementation's ABI when it's a proxy. Without payment returns the x402 challenge; pass x_payment to settle.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
chainYesEVM chain: ethereum | base | arbitrum | optimism | polygon | bsc.
addressYesContract address (0x + 40 hex).
x_paymentNox402 payment payload (base64) for this PAID decode. 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. Dates show when Glama detected each change.

  1. First observed

TDQS

A4.7/5.0
Behavior5/5

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

With no annotations, the description carries the full burden and excels: it discloses the $0.002 fee, the x402 payment mechanism, the order of operations (challenge first, then settle), the proxy standards handled (EIP-1967/1822/OZ-legacy/beacon), and the verification sources (Sourcify or Blockscout). This is far more transparent than typical.

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?

Two dense sentences, front-loaded with the critical 'PAID' warning. All information earns its place: payment, inputs, outputs, proxy behavior, and fallback challenge. No fluff or repetition.

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?

Despite lacking an output schema, the description enumerates return values (ABI JSON, verification status/source, signatures, proxy-implementation ABI) and explains the 402 challenge fallback. It covers the essential aspects of a paid, multi-chain tool well enough for an agent to use it correctly.

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 coverage is 100%, so baseline is 3. The description adds value by tying the parameters into the payment flow: 'Give {address, chain}' and 'pass x_payment to settle.' It clarifies the role of x_payment beyond the schema's description, making the interaction model concrete.

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 uses a specific verb ('fetch') and resource ('verified ABI + metadata for a contract'), and lists the exact outputs: ABI JSON, verification status/source, callable signatures, and proxy resolution. It clearly distinguishes from sibling decoding tools by focusing on ABI retrieval rather than data decoding.

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 explicitly explains the payment flow: omit x_payment to get a 402 challenge, then pass x_payment to settle. It implies when to use the tool (whenever a verified ABI is needed) but does not explicitly name alternatives or exclusions. Still, the context is clear and actionable.

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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TDQS

A4.5/5.0
Disambiguation5/5

Each tool has a clearly distinct purpose: fetching ABIs, decoding function calldata, decoding event logs, and resolving selectors/topics. There is no overlap in what they do, and their scopes are mutually exclusive.

Naming Consistency4/5

All names are lowercase snake_case and concise, but they mix verb-first (decode_calldata, decode_log) with noun-first (abi_fetch, selector_lookup) patterns. This is a minor deviation from a uniform verb_noun convention, but still predictable and readable.

Tool Count5/5

Four tools is a well-scoped size for a specialized decoding server. Each tool covers a necessary step in the decoding workflow without redundancy or bloat.

Completeness5/5

The tool set covers ABI retrieval, calldata decoding, event log decoding, and signature lookup, providing a complete lifecycle for decoding EVM data with no obvious dead ends. Optional ABI inputs allow flexible fallback to public sources.

Resources