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

With no annotations, the description carries the full burden and does so well: it discloses the source of truth (runtime tz database), the exact return payload (offset, abbreviation, DST flag, UTC instant, hour delta), and the two tricky edge cases (non-existent and ambiguous times). It even discloses cost and payment rail ($0.005/call over x402 USDC), which is genuinely useful for agent decision-making.

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?

Four sentences, all front-loaded and each earning its place: purpose, return shape, edge-case warning, pricing. No repetition of the name or schema.

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 must describe the return payload — which it does explicitly. Combined with full schema coverage of inputs and clear behavioral/cost disclosure, nothing an agent needs 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 description coverage is 100%, so the schema already documents from/to/time with formats and defaults. The description adds no parameter-level syntax or constraints beyond what the schema provides, so the baseline 3 applies.

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+resource (convert a time between two IANA time zones) and immediately scopes it with DST handling. An agent can distinguish this from time_now (current time) and time_zones (zone listing) without opening any 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?

Usage is implied by the description — this is the tool for zone-to-zone conversion, and hand-made conversion is called out as error-prone. However, no sibling is named or routed to (time_now, time_zones), and no explicit when-to-use/when-not guidance is given.

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