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

With no annotations present, the description carries the full burden and delivers meaningful behavior: it discloses the signature source (openchain DB), warns about specific risky functions (approve/setApprovalForAll/permit/unlimited amounts), and states a per-call cost of $0.005. It omits auth requirements, rate limits, and behavior on undecodable data, keeping it below 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?

A single front-loaded sentence that packs purpose, output contents, and cost with no filler. Every clause 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?

With no output schema, the description must describe return values, and it does so explicitly (signature candidates, decoded args, warnings). For a one-param decode tool, this covers everything an agent needs to invoke it correctly.

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 coverage is 0% and the single required param has no description, but the schema's regex pattern does constrain the format to hex calldata. The description implies the input is EVM calldata to be decoded but adds no syntax, length, or edge-case detail beyond that.

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?

Specific verb (decode) plus resource (EVM calldata) with explicit scope and intent (before signing), and it enumerates the outputs: signature candidates, decoded args, plain-English warnings. It is clearly distinguishable from siblings like ethereum_tx_explain and ethereum_token_approvals.

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?

"Before signing" gives a clear situational trigger that tells the agent when this tool applies. It stops short of naming an alternative tool or stating exclusions, so it is context-rich but not fully routing.

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