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

Goes well beyond the readOnlyHint/openWorldHint annotations by disclosing the cost model: $0.002 in USDC per successful call, payable via x402 on Base, Solana or Arc, with failed calls not charged. It also names the data source ('the page's embedded data', 'reads the public page, not the paid API'), which matters for freshness and reliability expectations.

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?

A single dense paragraph in which every clause earns its place: field list, scope exclusion, source, and billing terms. Scope and cost information are both front-loaded before an agent commits to a paid call.

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?

An output schema exists so return values need not be explained, yet the description still enumerates the fields returned. Combined with the explicit pricing, payment rails, and failure-billing policy, an agent has everything needed to decide and call correctly.

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?

Only one optional parameter (limit) exists and the schema documents it fully at 100% coverage, including the 1-100 range and default of 10. The description adds nothing about the limit parameter, so the baseline of 3 applies since the schema carries the semantics.

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 verb and resource ('Recently added tokens on CoinMarketCap') plus the exact field set returned (name, symbol, date added, price, 24h change, 24h volume, market cap). It also carves out scope by naming what is NOT included ('Exchange volume rank is not on this page and is not reported'), which lets an agent distinguish it from broader CoinMarketCap offerings without opening the schema.

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?

Makes clear this is the public new-listings page rather than the paid API, which is the key routing decision against the sibling finance_coinmarketcap entry. It gives clear context for use but does not explicitly name the alternative tool or state exclusions like 'use finance_coinmarketcap for historical or ranked data'.

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