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

Annotations already declare readOnlyHint and openWorldHint. The description adds value by stating 'Pure computation — no RPC call needed', which clarifies that no network interaction occurs and results are deterministic. It also indicates the input comes from transaction receipt logs, adding context beyond the annotations. There is no contradiction.

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 two sentences, with the first sentence stating the core purpose and the second providing a key behavioral note. It is concise, front-loaded, and contains no filler words. Every sentence adds value.

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?

The tool is a decode function with well-documented parameters and annotations covering safety. The description explains the input source and pure-computation nature, which is sufficient for an agent to understand the tool's role. There is no output schema, but the phrase 'into named fields' gives a basic expectation. It lacks explicit details about output structure or error handling, but this is acceptable given the established pattern of decoder tools.

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?

The input schema already provides detailed descriptions for all three parameters, including topics[0] as event signature hash, data as non-indexed parameters, and abi as JSON array or string. The description's mention of 'topics and data' adds no new semantic detail beyond the schema. Since schema coverage is 100%, a baseline of 3 is appropriate.

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 decodes raw event logs using topics and data, with a provided ABI, on Mezo testnet. It distinguishes itself from sibling decode tools by specifying the network (Mezo testnet) and the specific input type (event logs). The verb 'decode' and resource 'raw event log' are specific and unambiguous.

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 guidance on when to use it: 'Pass topics and data from a transaction receipt log entry' and notes 'pure computation — no RPC call needed'. This implies it should be used when you have a log entry from a receipt and want a decoded result without network calls. However, it doesn't explicitly compare with alternatives like eth_decode_log or mezo_decode_log, but the network-specific name and context make the intended usage clear.

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