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

Discloses that this is a pure computation with no RPC call, adding valuable context beyond the readOnlyHint and openWorldHint annotations. It specifies how to obtain the input ('from a transaction input or eth_call') but does not cover error cases or ABI mismatch behavior, keeping it from a 5.

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

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

Two well-structured sentences, front-loaded with the main purpose and no redundant information. Every phrase earns its place.

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

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

For a simple two-parameter tool, the description covers the purpose, network, and input sources. It partially specifies the output ('function name and typed arguments') but lacks details on failure modes or output structure, which would be useful since no output schema is provided.

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

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

Schema description coverage is 100%, so the baseline is 3. The description adds minor context about the calldata source ('from a transaction input or eth_call') but does not substantially enhance what the schema already documents for the abi and calldata parameters.

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

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

The description clearly states the verb 'Decode', the resource 'raw calldata', and the output 'function name and typed arguments', while specifying the context 'on Mezo testnet'. This distinguishes it from sibling tools like eth_decode_calldata and mezo_decode_calldata by network and input type.

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

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

It provides clear usage context by stating 'Pass the hex calldata from a transaction input or eth_call' and emphasizes 'Pure computation — no RPC call needed'. However, it does not explicitly mention alternatives or exclusion criteria, so it misses the top score.

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