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

Annotations already cover read-only, open-world and non-destructive status, but the description adds real value beyond them: an explicit cost ($0.002/call, first 25 free, failed calls free) and the warning that repeats are not free, which explains the idempotentHint=false in practical terms. It does not cover rate limits, latency, or response shape details, so it is strong but not exhaustive.

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?

Front-loaded with the resource definition, then use cases, then commercial/safety terms — a sensible order with no filler. Every clause carries either scope, use, cost, or safety 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?

No output schema exists, so the description compensates by listing the returned fields and the extra trending-categories section. Combined with cost terms and the read-only guarantee, an agent has everything needed to decide and call correctly for a single-optional-param 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?

With one optional parameter at 100% schema coverage, the schema fully documents `only` including its comma-separated syntax and empty-match fallback, so baseline 3 applies. The description only indirectly helps by enumerating the result fields an agent could project, but never mentions the `only` parameter itself.

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 and its exact provenance: coins most searched on CoinGecko in the last 24 hours, in rank order, with the named fields (price, 24h change, market cap, volume, rank, categories). That is clearly distinct from price-lookup siblings like crypto_price or price_token, and from dex_trending's on-chain pool focus.

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?

Gives concrete use cases (spot market attention, feed a news/trading agent, pick research targets), which tells the agent when this is the right tool. It stops short of naming an alternative tool or an explicit when-not-to-use condition, so it misses the top band.

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