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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower, and the description still adds value by describing what comes back: every common written form, the plain-English name for midnight/noon, and the chart hour. That last part overlaps somewhat with the existing output schema, keeping it just short of a 5.

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?

Three tightly written sentences, front-loaded with the core conversion and followed by input routing and an alternative. Minor waste in the return-value sentence, which partly restates what the output schema will already show.

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 a simple 4-parameter, zero-required tool with full schema coverage, annotations and an output schema, the description covers purpose, both input paths, accepted formats and sibling routing. Nothing an agent needs to call it correctly is missing.

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 coverage is 100%, so the baseline is 3, but the description adds real meaning: it shows accepted input formats for military_time ('1345, 13:45 or 0800') and reveals that colon-separated and bare forms are both valid, which the schema's maxLength 10 alone does not convey. It also clarifies the either/or relationship between the two input paths.

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?

States a specific verb (convert) and resource (military/12-hour time), explicitly bidirectional, and names the sibling it is not (military_shift_hours) with the reason. An agent can distinguish it from the other time tools without opening a schema.

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?

Gives explicit input paths — 'Give military_time ... to get the standard time, or hour_12, minute and period to get the military time' — and explicitly routes the interval use case to military_shift_hours. Both when-to-use and the alternative are spelled out.

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