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

Annotations already cover the safety profile (readOnlyHint=true, idempotentHint=true, closed-world), so the bar is lower. The description usefully adds the output formats and time-zone-aware conversion behavior, but says nothing about how ambiguous epoch values are disambiguated under unit='auto' or how conflicts between 'input' and the calendar fields are resolved, which is the risky part of this 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?

A single front-loaded sentence that packs the input units, both output formats, time-zone scoping, and the bidirectional capability with zero filler. Nothing can be cut without losing semantic content.

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?

An output schema exists, so return values need not be described, and annotations handle safety. However, for a 9-parameter tool with 22% schema coverage and a dual input mode, the description omits how to supply calendar input, how the five unit options interact with 'auto', and that 'input' also accepts ISO-8601/RFC 2822/'now' — gaps an agent would hit on first use.

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 description coverage is only 22%, so the description carries most of the burden — and it does not. Six numeric calendar parameters (year, month, day, hour, minute, second) and the 'unit' enum are never mapped to meaning, and the crucial mode-selection rule (leave 'input' empty when calendar fields are set) appears only in the schema, not the description. The unit and time-zone mentions largely restate enum/default values already present in 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?

States a specific verb (convert) and resource (unix timestamp/epoch) plus the exact accepted units (s, ms, us, ns) and output formats (ISO-8601, RFC 2822). It also declares the reverse direction ('calendar time back to epoch'), which clearly separates it from the sibling date_difference without opening either 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?

The description implies the two usage modes (epoch input vs. calendar components) so an agent can infer direction, but it never states when to prefer this tool over date_difference or convert_data_format, nor does it explain the 'auto' unit-detection behavior that governs the no-unit case. Usage is implied rather than prescribed.

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