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

With readOnlyHint/idempotentHint already declaring the safety profile, the description still adds substantial context the annotations cannot: the $0.002/call price, 10 free calls per day, the x402 payment-required result, fuzzy-match behavior that returns best match plus alternatives, and error semantics (isError message, not charged).

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-loaded with the payload contents, then input format, then cost/error semantics — a sensible ordering with no filler sentences. It is dense and slightly packed (data-source sentence, pricing, errors, fuzzy matching all in one paragraph), but every sentence carries actionable information.

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?

An output schema exists so return values need no explanation, and the description covers everything else an agent needs: what is returned, accepted input forms, fuzzy-match side effects, cost, and error/charging behavior. No material gap remains for a single-parameter lookup.

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% for the single 'protocol' parameter, so baseline is 3. The description adds value beyond the schema by giving example slugs with varied casing/naming ('aave', 'Uniswap', 'jupiter') and explaining fuzzy-match resolution behavior, which shapes how the agent should format input.

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 ('One DeFi protocol in depth') and enumerates exactly what the profile contains: TVL by chain, TVL trend, fees/revenue across three windows, market cap, audits, links. The 'one protocol' scoping implicitly distinguishes it from list-style siblings such as defi_rankings, chain_tvl, and fees_revenue.

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 clearly states the lookup key ('by name or DefiLlama slug') and gives concrete slug examples, so an agent knows the calling context. However, it never explicitly routes the agent away from siblings like defi_rankings (multi-protocol lists) or chain_tvl (chain-level TVL) — no 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.