Convert time zones

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

Annotations already cover read-only and idempotent behavior, so the description's added value is the DST-awareness note and the pricing model (25 free calls/day, then $0.001 via x402) – real operational information an agent cannot get from structured fields. It says nothing about invalid-timezone handling or output shape, but an output schema exists to cover the latter.

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 tight clauses: what it does, when to use it, and cost. Front-loaded and free of filler, though the pricing sentence is somewhat tangential to correct invocation.

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?

A low-complexity, three-parameter conversion tool with an output schema and annotations that already signal safety and idempotency. The description adds DST and pricing context; only edge-case behavior for invalid or ambiguous local times is left unaddressed.

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 only 33%, and the description partially compensates by specifying IANA names and mentioning UTC offsets. However, it does not explain the interaction where a naive local datetime requires from_timezone, nor which timezone is required – that nuance lives only in the schema.

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: convert a time between time zones, DST-aware. This is clear enough to distinguish it from date_add or date_diff, though it never names a sibling such as city_time to close the gap.

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?

Gives concrete usage contexts ('what time is 3pm Manila in New York', scheduling across zones, UTC offsets), which tells the agent when this tool applies. It provides no explicit exclusions or rival-tool routing, so it stops short of a 5.

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