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

With no annotations supplied, the description carries real weight here: it discloses the price ($0.01 USDC on Base or Solana), that no account or API key is required, that failed calls are not billed, and the upstream data source. It omits pagination behavior and result shape beyond 'APY and TVL', so the billing-matters disclosure is strong but return-side behavior is thin.

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?

A compact block with zero filler: what it returns, the data source, the price, the payment rails, the auth model, the billing policy, and the endpoint URL. The core resource statement is front-loaded right before the commercial terms.

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 three-optional-parameter paid read tool with no output schema and no annotations, the description covers the commercial, auth, and sourcing context an agent needs plus the headline return fields. What is missing is whether results are a flat pool list and how they are ordered by default, both of which the agent must guess.

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 all three parameters (sort, limit, min_tvl_usd) carry their own descriptions including defaults, so the schema does the heavy lifting. The description adds no meaning about sort ordering or how min_tvl_usd affects results, which is the baseline 3 case.

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 resource and scope: live yield pools holding METH across protocols and chains, returning APY and TVL from DefiLlama. The METH token focus separates it from the buy_yields_token_* siblings and the chain/protocol variants named in the tool name, though the description never explicitly routes to those alternatives.

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?

Implies usage ('where to earn yield on METH') and gives operational invocation context (paid, no account, no key, failed calls not charged), but never says when to prefer buy_yields_protocol_meth-protocol or buy_yields_chain_* over this token-level view. The consumer must infer the selection rule from the tool name.

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