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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false, covering safety. The description adds valuable behavioral details: pricing per call, a free daily quota, ranking with day-over-day change, and the semantics of fees vs revenue. These go beyond the annotations and inform the agent about cost and output characteristics.

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 moderately sized and front-loaded with the core purpose. It defines key terms and includes cost info, all in a readable format. A minor redundancy is the metaphorical 'cash-flow view' but it adds flavor without bloat. Overall 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 describe the response structure; it mentions 'Ranked, with day-over-day change' but not the exact shape. The time period selection is ambiguous since no parameter exists, and 'limit' is not explained. It covers the main query intent but leaves several operational details unclear for a tool with only 3 parameters.

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 only 33% (chain just says 'optional'). The description explains 'chain' and 'metric' (fees/revenue) but does not explain 'limit' or clarify that time ranges (24h/7d/30d) are not parameters—this is ambiguous since no period field exists in the schema. The description partially compensates but leaves key parameters under-specified and introduces confusion about time selection.

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 purpose: reporting fees and revenue for protocols and chains, with time ranges and chain filtering. It defines key terms (fees vs revenue) and distinguishes the 'cash-flow view' from other data. While it doesn't name a sibling, the specificity makes the intent 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 description gives context on what the tool does (fees/revenue, time periods, chain filter) but provides no guidance on when to choose this over alternative tools like defi_rankings or chain_tvl. No exclusions or comparisons are mentioned, so the agent must infer suitability from the purpose alone.

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