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

Annotations only declare readOnlyHint and openWorldHint. The description adds pricing ($0.002 USDC via x402 on specific chains), that failed calls are free, attribution, and that protocol results omit change figures. That's real behavioral context beyond annotations, though it omits rate limits and the fact that no parameters returns something ambiguous.

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 purpose well, but the pricing, attribution, and disclaimer clauses add bulk that pushes the important operational constraint (no history) into a buried middle sentence.

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?

Covers the two input modes, the protocol-vs-chain output difference, cost mechanics, and attribution. With an output schema present and 100% schema coverage, remaining gaps are minor; ambiguity about zero-parameter calls is the main omission.

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 coverage is 100% and the schema already documents both params, but the description usefully clarifies the protocol path yields only current TVL while the chain path yields 1d/7d changes, adding meaning about output shape.

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+resource: returns total value locked in DeFi from DefiLlama, and distinguishes inputs (protocol slug vs chain name). Clearly separable from siblings like defi_chains, defi_dex_volume, defi_fees, defi_stablecoins.

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?

Explains what each parameter class fetches and explicitly notes that a protocol's history is too large to read here, which is a useful boundary. However, it doesn't point to which sibling to use for historical TVL or chain lists.

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