get_current_datetime

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

With no annotations, the description carries the burden of behavioral disclosure. It thoroughly explains the return format (fields like ISO 8601, Jalali date, timezone info) and mentions error behavior for invalid timezone. This covers the tool's observable behavior well for a read-only utility.

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 well-structured with a summary, bulleted return fields, Args section, and examples. While slightly long, every section adds value and the structure aids scanning. No fluff or redundancy.

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 single-parameter tool with no siblings and no annotations, this description is fully complete. It covers purpose, parameters, return format, error handling, and examples. The output schema is described in detail, so an agent knows exactly what to expect.

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 schema provides only the name 'timezone' with no description (0% coverage). The description compensates fully: it explains the purpose, lists valid IANA examples, documents the default behavior, and provides usage examples. This adds complete semantic meaning beyond 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?

The description starts with a clear verb-object statement: 'Get the current date and time.' It then enumerates the exact data returned, making the tool's functionality unambiguous. No siblings exist, so distinction is automatically satisfied.

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 states when to use the optional timezone parameter and what happens if it's omitted ('If not provided, uses system local timezone'). Examples cover typical use cases. No exclusions or alternatives are needed since there are no sibling tools.

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