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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered; the description adds genuinely new behavioral context – the x402 pay-per-successful-call pricing at $0.05 USDC on Base or Solana, and the fact that each page is a separate billable lookup. It stops short of stating rate limits or whether failed lookups are charged (only 'successful' calls are, which is stated).

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 short sentences with zero filler: what it returns, how paging works, and what it costs. The resource and return fields are front-loaded before the operational caveats.

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 return fields, and it covers the cost/auth model that would otherwise be invisible. It omits how many results a page contains and how results are ranked, which an agent sizing a search loop would want, but nothing required to call it correctly is missing.

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 100%, so both 'keyword' and 'page' are already documented in the schema, and the description's mention of name search and per-page lookups adds only marginal framing. The important derived detail – that each page incurs its own charge – is conveyed, but not parameter-specific syntax or matching behavior.

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 ('Find public Discord servers by name') and enumerates what comes back (guild IDs, member counts, tags, invites), which immediately separates it from the username/tag/profile siblings in the list. An agent can tell this is server discovery, not user lookup, 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?

The description gives clear paging guidance ('request page 2+ only when hasMore is true'), but says nothing about when to choose this over discord_lookup or the other Discord siblings. Usage is inferable from the name and scope, not stated.

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