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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered and the bar is lower. Beyond that, the description adds no behavioral context: it does not mention the L402 payment gating implied by the l402_proof parameter (unpaid calls return an invoice), does not say what output form 'normalized UTC timestamp forms' actually is, and gives no error behavior for unparseable input.

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 with zero filler; the verb and the input formats come first and the output goal last. It is slightly under-sized for a tool that carries a payment flow, but nothing in the sentence is wasted.

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?

The tool is a simple 3-parameter converter with full schema coverage and no output schema, so the burden is modest and the description is adequate at a minimum-viable level. However, 'normalized UTC timestamp forms' is left undefined (RFC3339 string? epoch seconds?) and the L402 payment prerequisite, which an agent must know to succeed on the paid path, appears only in the schema rather than being surfaced in the description.

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 100%, so baseline is 3. The description's format list does mirror and reinforce the 'from' enum values (unix, unix_ms, rfc3339, date), but it adds no meaning about the 'auto' inference behavior, the expected string shape of 'value' per format, or the payment flow for l402_proof beyond what the schema text already says.

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 names a specific verb (convert) and resource (timestamps) and enumerates the exact accepted input formats: Unix seconds, Unix milliseconds, RFC3339, and ISO dates. It also states the output direction (normalized UTC), so an agent can immediately tell this is a format-normalization utility and no sibling (base64_convert, hash_generate, url_parse, etc.) overlaps with it.

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 only implied: the listed formats suggest callers pass any of them, and the schema's 'auto' default implies inference. There is no explicit statement of when to use this versus siblings, no guidance on when to set 'from' explicitly rather than relying on 'auto', and no guidance on ambiguous inputs.

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