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

Annotations already declare readOnly, idempotent, non-destructive, open-world, so the safety profile is covered. The description adds meaningful non-schema context: a per-call price ($0.002/call) and an interpretive note that net new supply proxies fresh on-chain dollar liquidity. It does not discuss freshness or rate limits, keeping it short of a 5.

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?

Information-dense and front-loaded with the source and return shape; the long field enumeration is justified because there is no output schema. It is slightly heavy but every clause carries signal (fields, cost, interpretation, alternative).

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 no output schema, the description carries the full return contract (all three top-level keys and their sub-fields), plus cost and the sibling alternative. Nothing an agent needs to call it correctly is missing.

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 has 100% description coverage for the single 'limit' parameter, so the baseline is 3. The description adds no syntax, default, or interaction detail beyond what the schema already documents.

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 the specific resource ('Stablecoin supply from DefiLlama') and enumerates exactly what it returns (totals_usd_pegged, depegged_over_50bps[], items[] per stablecoin). It also names the sibling it is not (whale_moves), so an agent can route between them without opening schemas.

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?

Explicitly states when to use it ('total stablecoin supply and net change') and when to use the alternative ('for individual large transfers use whale_moves'). This is the full when/when-not/alternative pattern.

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