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

No annotations exist, so the description carries the burden. It clearly implies a read-only lookup with no destructive effects, which is adequate for a simple time tool. However, it does not disclose behavior for invalid timezone names, output format, or that most schema parameters are discarded beyond what the schema already says.

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 a single sentence with no filler, front-loading the essential operation. It earns its place and does not waste tokens.

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?

The definition leaves important invocation details ambiguous: required parameters are 0, yet the description implies a timezone must be provided; there is no output schema; and the presence of many unrelated accepted parameters is confusing without a clear statement that only 'zone' matters. An agent cannot fully predict the call contract from the description and schema alone.

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 each parameter. The description adds little beyond restating that an IANA timezone name is used, which mirrors the 'zone' parameter's schema description. The 'discarded' notes in the schema are useful but are not part of the description.

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 states a specific verb and resource: 'Current time in a named IANA timezone.' This makes the core purpose unmistakable and distinguishes it from related concepts. It doesn't explicitly differentiate from siblings like utc-time or iana-zones, but the meaning is still clear.

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 phrase 'named IANA timezone' implicitly suggests this tool is for zone-specific local time rather than UTC time, but there is no explicit when-to-use or when-not-to-use guidance. The agent must infer the choice among siblings like utc-time and iana-zones without direct routing help.

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