Timezone / DST convert (paid $0.001)

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

With no annotations, the description carries the full burden. It discloses the paid nature, the x402 payment flow (challenge vs. settlement), and the output fields (converted datetime, UTC offsets, tz abbreviations, DST flags, offset difference). It does not detail all error cases, but the key behavioral traits are transparently 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?

The description is concise and well-structured, leading with the crucial paid warning, then the core purpose, return fields, arguments, and payment flow. Every sentence is functional, though the density of information in one paragraph slightly reduces readability.

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 paid tool with no output schema, the description covers the essential context: payment mechanism, return values, required arguments, and a free alternative. It lacks explicit edge-case behavior (e.g., invalid zone handling) but is otherwise sufficiently complete for an agent to invoke it correctly.

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?

The input schema already provides 100% descriptive coverage for all four parameters, including formats and payment payload details. The description merely reiterates the args list and payment behavior without adding meaningful new semantics beyond what the schema already says, so a baseline of 3 is appropriate.

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?

The description clearly states the tool's function: 'Convert an instant between IANA time zones with historically-correct DST.' This is a specific verb+resource that distinguishes it from generic siblings like 'convert' or 'datemath', and it also lists the return fields.

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 provides clear context for when to use the tool: it is a paid timezone conversion tool. It explains the payment prerequisite ('Without payment returns the x402 challenge') and mentions an alternative ('Free teaser exists on the HTTP API'). However, it does not explicitly contrast with sibling tools or state when not to use it.

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