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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world). Beyond that, the description adds real behavioral context: a fixed 24-hour observation window and the specific currencies and fields covered, which tells the agent exactly what freshness to expect. No pagination or return-shape detail is given.

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?

Three tight sentences: payload first, then usage triggers, then exclusions. No filler, and the scope-defining content is 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 no output schema, the description usefully enumerates what comes back and the time window, which is enough to call the tool for a listing. The only real omission is any meaning for the sort parameter, leaving a small gap for a single-parameter tool.

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?

There is one parameter (sort) with 0% schema description coverage and an unexplained enum value ('points' is never mentioned in the description). The description lists output fields but says nothing about what sort controls or how the four enum modes differ, so it fails to compensate for the coverage gap.

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 the resource ('every app on Arc in the indices') and enumerates the exact payload (24h stablecoin payments in USDC/EURC, USD volume, verified status, first-seen hour). This implicitly separates it from siblings like arc_new_apps or arc_verified, though no sibling is named outright.

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?

Explicit positive triggers ('which apps use USDC on Arc, or which are most used') plus explicit exclusions ('Not for token prices, DeFi TVL or chains other than Arc'). It stops short of naming a concrete alternative sibling tool, so it is clear context rather than full when/when-not/alternative routing.

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