Stablecoins

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds genuinely useful context beyond annotations: the data source and freshness ('DefiLlama nightly'). It omits result-size/pagination behavior and whether data can be stale within the day.

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 compact sentences, front-loaded with the purpose before the filtering note, with no filler. The first sentence is dense with parentheticals but every clause carries 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?

With no output schema, the description usefully enumerates the returned fields (price vs peg, mechanism, 1d/7d/30d supply change) and notes data provenance, which is what an agent needs to judge fitness. The undocumented limit parameter and lack of pagination/default-size behavior are the remaining gaps.

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 0% and there are 3 params. The description compensates for symbol and peg by giving concrete peg values (peggedUSD, peggedEUR), which the schema lacks as an enum, but the limit parameter is never mentioned or bounded (schema caps at 100, default unknown).

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?

Names a specific resource (stablecoins ranked by circulating supply) and enumerates the returned attributes: price vs peg, mechanism, and supply change windows. No sibling in the list overlaps, though the description never explicitly says whether this returns a ranked list or a single record.

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?

The description gives filtering instructions ('Filter by symbol or peg type') but no when-to-use context, prerequisites, or boundaries (e.g., what happens with no filter, how many rows come back by default). Usage is implied rather than stated.

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