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

The annotation readOnlyHint already covers the read-only nature. The description adds no further behavioral details such as pagination behavior, error handling, or rate limits. It only restates the core function without additional transparency.

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 extremely concise, consisting of two short sentences. It conveys the essential purpose and a key constraint without any unnecessary wording, making it highly efficient.

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 should explain what 'full bodies' means and how the cursor works for pagination. It does not describe the return format or the interplay between selectors and cursor, leaving gaps in the complete usage context.

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 description does not explain the meaning or relationship of the 'selectors' and 'cursor' parameters. It does not clarify that selectors are an array of identifiers or that cursor is used for pagination, leaving the agent to infer from 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 fetches complete units for selectors already chosen, and explicitly says it does not discover selectors. This distinguishes it from sibling tools like web3_search or web3_lookup, making its purpose 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?

The phrase 'Does not discover selectors' implicitly tells the agent to use this tool when selectors are already known, not for discovery. It provides a clear negative usage guideline, though it does not explicitly mention alternatives like search or lookup tools.

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