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

With no annotations, the description carries the full burden and does substantial work: it discloses that calls are paid ($0.01 USDC on Base or Solana), that no account or API key is required, that failed calls are not charged, and it exposes the underlying endpoint URL. What it omits is operational behavior — rate limits, data refresh cadence, and response shape or pagination behavior for the row list.

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 front-loaded with the critical qualifier 'Paid.' and packs cost, access model, data source, and endpoint into two tight sentences with no filler. The trailing raw URL is slightly redundant with the tool name but is defensible for a paid HTTP endpoint the agent may need to reason about.

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 paid, zero-required-parameter read tool with no output schema and no annotations, the description supplies the commercial terms, billing behavior, data provenance, and the metrics returned — enough to decide and invoke confidently. The remaining gap is return-format and pagination detail, which is minor given the limit parameter is documented in the schema.

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 description coverage is 100%, so sort, limit, and min_tvl_usd already carry defaults and value ranges in the schema. The description's mention of APY and TVL implies what sorting and filtering operate on but adds no syntax, units, or edge-case guidance beyond the schema. Baseline 3 applies.

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 (live DeFi yields for the symbiotic protocol, aggregated across chains) and enumerates the returned metrics — APY, TVL, 7d APY change — plus the data source (DefiLlama). The word 'protocol' plus 'its pools' cleanly separates it from the sibling chain-, token-, and top-level yield tools without needing to name them.

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?

Usage is implied rather than stated: an agent can infer this is the right tool for protocol-level yield lookups on Symbiotic, but the description never says when to choose a sibling such as buy_yields_chain_base or buy_yields_token_eth instead, nor when a protocol-level aggregate is preferable to a chain-level one. The payment/commercial conditions are well covered, but selection guidance against alternatives is absent.

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