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

Annotations already cover the read-only, idempotent, non-destructive profile, so the description's job is to add context — and it does: it discloses the data source (DefiLlama fees and revenue dataset) and enumerates the returned columns, which matters because no output schema exists. The exclusion rule for 'change' sorting appears only in the schema, not the description.

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?

Front-loads the core ranking action and periods, then questions answered, filters, and row shape. The row enumeration is long but justified by the absence of an output schema; no sentence is pure filler.

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?

For a six-param, no-output-schema, read-only ranking tool, the description covers purpose, filters, source, and return columns, which is enough to invoke it correctly. It stops short of describing ordering/pagination behavior beyond the schema's limit and sort_by.

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 100% and all six params are documented there, including enums and the $10k prior-revenue exclusion for sort_by=change. The description adds only category examples ('Dexs', 'Lending', 'Liquid Staking') that largely duplicate the schema, so baseline 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?

States a specific verb and resource ('Rank DeFi protocols by revenue (or fees)') plus the ranking windows and that it includes change versus the prior period. It also names the sibling it hands off to (defi_protocol_fees) for daily series, so an agent can distinguish it from the other defi_* tools.

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?

Quotes the natural-language questions it answers ('top DeFi protocols by 30-day revenue', 'which protocols' revenue grew most') and explains filtering by category and chain, which gives clear selection context. The routing to defi_protocol_fees is explicit, but there is no statement of when this tool is the wrong choice.

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