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

Beyond the readOnlyHint and openWorldHint annotations, the description discloses important behavioral details: the call costs $0.002 in USDC via x402 on Base, Solana, or Arc, and failed calls are not charged. It also clarifies that only the current TVL number is returned, not a breakdown or history, which is valuable behavioral context.

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 three tightly written sentences with no wasted text. The core purpose and scope are front-loaded, followed by the return limitation and payment terms, all of which earn their place.

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?

Given that an output schema exists and annotations already declare read-only/open-world behavior, the description provides everything needed: what is returned, what is excluded, parameter examples, and payment semantics. No critical invocation detail is missing.

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 schema has 100% description coverage for the single parameter, so the baseline would be 3. The description adds concrete examples such as 'aave' and 'uniswap-v3', which help the agent understand the expected protocol slug format beyond the schema's generic lowercase/digit/dash constraint.

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 states a specific verb-like operation and resource: fetch the current total value locked in USD for one DeFi protocol from DefiLlama. It also scopes the result by noting that only the single current TVL number is returned, with chain breakdown and history excluded, which clearly differentiates it from broader DefiLlama or historical analytics 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?

It gives clear usage context by saying this returns only the current TVL number and not chain breakdown or history, which implies when it should and should not be used. However, it does not explicitly name alternative sibling tools for chain-level or historical TVL data, so it falls short of full when-to-use/when-not-to-use guidance.

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