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

Annotations only declare readOnlyHint and openWorldHint; the description adds genuinely useful behavior beyond them — that coverage is limited to the current thread, that results carry contact emails and links, and a concrete cost model (x402 payment, $0.01 USDC on three chains, no charge on failure). It does not cover pagination or how many results the thread yields per call.

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?

Two sentences with zero filler: the first front-loads what is searched and what comes back, the second covers the payment condition. Nothing is repeated from the title or annotations.

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?

For a three-optional-parameter read tool with an output schema, the description covers scope, filters, and cost adequately. The remaining gap is thread lifecycle detail (what 'current' means when the monthly thread rolls over) and pagination behavior, both minor given the output schema exists.

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 description coverage is 100%, so the schema already documents q, limit, and remote, and the baseline is 3. The description adds mild meaning by implying keyword matching and the remote filter, but does not clarify limit behavior or the odd string typing of limit/remote.

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 — 'Search the current Hacker News Who is hiring? thread' — plus what it returns (companies, contact emails, links). It is clearly distinct from generic siblings like hn or hn_search, though it never names them to make the contrast explicit.

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?

Usage is implied by the keyword and remote filtering plus the 'current thread' scoping, but there is no explicit when-to-use or when-not guidance, and no pointer to hn_search for historical or non-hiring HN queries. The pricing note helps an agent decide whether to call, but that is a cost signal, not a selection rule.

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