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

The annotations already declare read-only, idempotent, non-destructive behavior. The description adds useful context beyond that: supported strftime tokens, strict rejection of impossible dates such as 31 February, and a 1-credit cost. It does not describe the exact return shape, but behavior is otherwise well covered.

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 two front-loaded sentences plus a short cost note, with no wasted wording. The most important information, format conversion and supported strftime codes, comes first.

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?

This is a low-complexity formatting tool with rich annotations and full schema coverage. The description covers the format syntax and invalid-date behavior sufficiently for an agent to call it correctly, and no output schema is needed.

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 baseline would be 3. The description still adds meaning by listing supported strftime codes and clarifying that time is optional while impossible dates are rejected rather than normalized.

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 a date, with optional time, from one format to another using strftime codes. It is clear, but it does not explicitly distinguish itself from date/time siblings such as convert_time.

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 use case is implied by the description, but there is no explicit when-to-use or when-not-to-use guidance, and no alternative tools are named. It is the minimum viable level for a straightforward formatting tool.

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