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

Annotations already declare readOnlyHint and openWorldHint, but the description adds meaningful behavioral detail: 'Pure computation — no RPC call needed' and 'using a provided ABI.' This clarifies that the tool does not fetch data from the blockchain and requires the caller to supply the ABI, going beyond the annotations.

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?

The description is three short sentences, front-loaded with the core purpose, followed by essential behavioral and usage notes. Every sentence contributes meaningful information; there is no fluff or redundancy.

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?

Given the tool's simplicity, no output schema, and good annotations, the description covers the key points: what it does, input source, and offline nature. It doesn't describe error cases or output format in detail, but those are secondary for a pure decode operation with a well-defined input. It is nearly complete.

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 100%, so baseline is 3. The description adds semantic context by stating that topics and data come 'from a transaction receipt log entry,' and refers to the input as 'a raw event log (topics + data).' This helps the agent understand the real-world source of the parameters, adding value over the schema alone.

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 tool's function: decode a raw event log into named fields using a provided ABI. It specifies both the verb ('decode') and the resource ('raw event log'), and differentiates from sibling tools by explicitly mentioning 'Ethereum mainnet' and 'log' (as opposed to calldata or return).

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?

The description provides clear context for usage: 'Pass topics and data from a transaction receipt log entry' and 'Pure computation — no RPC call needed.' This tells the agent when to use it (when raw log data is available) but does not explicitly name alternatives or exclusions, so it misses the highest bar.

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