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

Annotations already mark the tool as read-only/idempotent and non-destructive, and the description adds useful context: the data source, protocol count, output row fields, and the fact that it is free. It stops short of describing pagination or response format details, but the annotations cover the safety profile well.

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?

Four tight sentences pack the core behavior, filtering options, output row fields, example uses, and cost into a compact description. It is front-loaded with the main purpose and contains no 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?

With no output schema, the description compensates by enumerating exactly which fields appear in each row and stating the data source and scope (~6,000 protocols). All parameters have defaults or enums, and the examples anchor correct usage, so an agent has enough to call this tool correctly.

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 clarifies sort semantics ('by TVL (or 1 d / 7 d TVL change)') and gives concrete chain/category examples, adding value beyond the schema. However, schema description coverage is only 40% and the description does not mention min_tvl_usd or limit, so the agent has to infer their behavior from names/defaults.

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 names a specific resource (Top DeFi protocols from DefiLlama) and a clear ranking/filtering action ('by TVL or 1 d / 7 d TVL change', 'filterable by chain and category'). It also gives concrete queries like 'biggest lending protocols on Base', which distinguishes this list-oriented tool from per-protocol or chain-level siblings.

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 explicit use-case examples ('biggest lending protocols on Base', 'fastest growing DEXes this week'), so an agent knows what kinds of questions this tool answers. It does not explicitly mention when to prefer a sibling tool like defi_protocol or chain_tvl, hence no exclusions/alternatives guidance.

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