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

Annotations already declare readOnlyHint=true, idempotentHint=true, and openWorldHint=false. The description adds useful behavioral context beyond annotations by specifying that daylight saving is applied for the given date and that a world clock is included. It does not cover return formatting or edge cases, but it meaningfully exceeds the annotation baseline.

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: two sentences plus a reference URL. It leads with a memorable example rather than the purpose, but contains no filler and every element contributes to understanding the tool.

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 simple, read-only converter with three optional parameters and no output schema, the description covers purpose, DST handling, world clock, and an example. It does not fully specify the return structure, but the behavioral context and annotations make it largely complete.

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%, and the schema already defines the two enum-based city parameters with defaults and the 'when' format. The description adds a concrete example ('9:00 AM in New York is 2:00 PM in London in summer') but does not clarify the to/from/when parameters beyond what the schema provides, so the baseline of 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?

The description states a specific verb and resource: convert any date and time between two cities, with daylight saving applied for that date. It clearly identifies the tool's purpose but does not explicitly differentiate it from similar sibling tools such as date_difference_calculator or unix_timestamp_converter.

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's focus on converting date and time between two cities, and the schema's 'when' parameter notes that leaving it empty uses the current time. However, there is no explicit when-to-use guidance, when-not guidance, or mention of alternative tools.

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