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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description adds useful context beyond that: the data source (DefiLlama), output format (JSON), and a monetary cost for the call ($0.03 USDC via x402). It does not contradict annotations and gives the agent practical behavioral expectations about cost and response type.

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 a single, well-structured sentence that front-loads the purpose and then lists the returned data fields. It also packs in the source, format, and pricing without unnecessary wording. Every clause earns its 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?

For a simple single-parameter tool with no output schema, the description covers the essential input (slug), the full set of return values, the data origin, the output format, and the cost. Enough information is present for an agent to select and invoke the tool correctly without ambiguity.

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 already fully documents the single parameter 'slug' with examples (aave, uniswap, lido), and the description reinforces that the slug is a DeFi protocol slug. Since schema coverage is 100%, the description adds marginal semantic value beyond the schema, staying within the baseline.

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 operation: retrieving a DeFi protocol brief by slug for one protocol, and enumerates the returned fields (TVL, category, chains with per-chain TVL, audit status, one-line description). It clearly distinguishes this tool from crypto-related siblings like crypto_balance or crypto_token_report by focusing on protocol-level metrics from DefiLlama.

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 clear context for when to use this tool: when you need a DeFi protocol-level overview in a single call using a protocol slug. It does not explicitly mention alternatives or exclusions, but the scope is specific enough that an agent can infer it is not for wallet balances, gas fees, or individual token reports.

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