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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, open-world), and the description adds substantial beyond it: the x402 pricing model ($0.01 per call), the prepaid x-credit-token header for unlimited calls, the absence of a free tier, and that no API key is required. The 'new ≠ safe' warning and the b20-safety routing are real behavioral context an agent needs before invoking.

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 core purpose before details, and the pricing/header clauses are separated from the functional description. It is dense with em-dashes and slightly marketing-flavored, but every sentence (fields, discovery framing, safety warning, pricing) carries information an agent can act on.

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?

Output schema exists, so return values need not be explained, and the description still names the key fields. Pricing, auth model, and safety follow-up are all disclosed. The only gap is the vague semantics of the `limit` parameter, which neither schema nor description clarifies.

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 parameter (limit) with 100% schema coverage, though its schema text ('How many') is terse. The description adds no meaning to the limit parameter, so the baseline of 3 applies when the schema carries the load.

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?

Specific verb+resource: lists the newest B20 tokens on Base from the B20Factory precompile, and even names the returned fields (variant, symbol, decimals, block). It scopes itself to B20 tokens, implicitly narrowing against generic siblings like new_tokens/trending_tokens, but never explicitly contrasts with them, so it falls short of full sibling differentiation.

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?

Frames itself as 'a discovery feed for agents hunting new B20 launches early' and gives a concrete follow-up instruction ('Run b20-safety on any address before touching it — new ≠ safe'). It does not state when to prefer this over new_tokens or trending_tokens, so there is context but no explicit alternatives or exclusions.

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