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

With no annotations, the description carries the burden and does well: it discloses that the unit (seconds/ms/µs/ns) is auto-detected, that time-zone rules apply to offset-less dates, and that extra fields (weekday, ISO week, relative time) are returned. It omits any note on ambiguous or out-of-range input handling, but that is a modest gap for a pure-computation tool.

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?

Two sentences, both essential: the first defines the bidirectional conversion, the second covers the secondary return values. Front-loaded with the primary purpose and free of filler.

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 two-parameter utility with no output schema and no annotations, the description covers input formats, unit detection, timezone semantics, and the returned fields. Nothing an agent needs to invoke 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 explains unit auto-detection for `value` (absent from the schema) and clarifies that `timezone` governs display plus offset-less dates while an explicit offset in the input wins. That precedence rule is behavioral detail beyond the schema text.

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 (convert) with both directions spelled out: Unix timestamp (sec/ms/µs/ns, auto-detected) → readable date, and date/time string → Unix timestamp. This is unambiguous and clearly differentiates it from siblings like date_calc (arithmetic) and get_current_time (clock reading).

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?

Usage is implied by the accepted input formats rather than explicitly stated. It never says when to prefer this over date_calc or get_current_time, nor does it warn about ambiguous inputs, so the agent must infer routing from the tool name alone.

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