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 only states high-level operations ('Format and parse time durations') but does not disclose accepted duration formats, output shape, error behavior, or whether this is a read-only transformation. This is a significant gap for correct invocation.

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 short and front-loaded, but the 'Duration:' prefix largely repeats the tool name and adds no value. The remaining clause is efficient but minimal; it captures the domain and operations without unnecessary words, though it sacrifices substance for brevity.

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 tool with no output schema and no annotations, the description should clarify the expected input format and return value, but it does neither. The presence of sibling tools like duration-iso and duration-humanize makes the ambiguity especially costly, since an agent cannot reliably distinguish or invoke this 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 schema already documents the only parameter as 'Duration to process' with 100% coverage, so the baseline is 3. The description adds the operations (format/parse) but does not clarify what format the duration should be in or what the parsed/formatted result should look like. It neither meaningfully enriches the schema nor leaves the parameter entirely unexplained.

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 clear verb and resource: 'Format and parse time durations.' It explains that the tool handles two operations on duration values. However, it does not differentiate from closely related siblings such as duration-iso, duration-humanize, duration-human, or elapsed-time, so the agent may not know which duration tool to select.

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?

There is no guidance about when to use this tool versus the many duration-related alternatives, such as duration-iso or duration-humanize. The description gives no exclusions, no preferred input conventions, and no context clues for routing.

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