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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely new context: the list is ordered exactly as Pendle returns it (no client-side re-sorting), and calls are metered at $0.002 USDC via x402 with failed calls free — key for an agent deciding whether to call.

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?

Two dense sentences: what you get first, then sort behavior and limit, then cost. No filler, and the most decision-relevant facts are front-loaded.

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?

With an output schema and read-only annotations present, the description only needs purpose, ordering, cost and the limit hint — all supplied. A minor gap is that it doesn't note whether expired/matured markets are excluded or how fresh the data is.

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 single 'limit' parameter already documents its 1–50 range and default of 10. The description only adds that limit caps the list, which is essentially restating 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?

States a specific resource (Pendle Finance active yield markets on Ethereum) plus the exact return fields (name, expiry, implied APY, aggregated APY, liquidity) and data source (Pendle's public v2 API). This clearly separates it from generic yield siblings like crypto_defillama_yields or finance_defirate_yields.

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 only implied: the description tells you it lists active markets and that 'limit' caps the list, but never says when to pick this over the several yield/TVL siblings, nor any exclusion such as expired markets or non-Ethereum chains.

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