formatted_datetime

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It effectively describes key behaviors: it returns formatted datetime, uses strftime-compatible format strings, has a default format, returns a dictionary with status and formatted fields, and handles invalid formats with error responses. This covers most essential aspects, though it doesn't mention rate limits, authentication needs, or side effects (which may not be relevant here).

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 clear sections (Parameters, Returns) and front-loaded purpose statement. Every sentence adds value: the first states the core functionality, the parameter section explains format details, and the return section describes output structure and error handling. It could be slightly more concise by integrating the optional/default note into the main description, but it's efficiently organized.

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?

Given the tool's low complexity (1 optional parameter), no annotations, and the presence of an output schema (which the description references), the description is complete. It explains what the tool does, how to use the parameter, what it returns, and error behavior. The output schema details are appropriately referenced rather than duplicated, making this sufficient for an agent to invoke the tool 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 description adds significant value beyond the input schema, which has 0% description coverage. It explains that the 'format' parameter is a 'strftime-compatible format string' with a specific default, clarifies it's optional, and describes error handling for invalid formats. This fully compensates for the schema's lack of documentation, providing clear semantic meaning for the single parameter.

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 purpose: 'Return the current date and time using a custom format.' It specifies the verb ('Return'), resource ('current date and time'), and key differentiator ('custom format'). However, it doesn't explicitly distinguish this from sibling tools like 'current_datetime' or 'timezone_datetime', which likely provide similar functionality without format customization.

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 no guidance on when to use this tool versus its siblings. With multiple time-related tools available (e.g., 'current_datetime', 'timezone_datetime', 'unix_timestamp'), there's no indication of when this format-based approach is preferable, nor any mention of prerequisites or alternatives. Usage is implied through the parameter description but not explicitly stated.

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