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

With no annotations, the description carries the full burden and does well: it discloses determinism (no LLM guessing), that relative expressions are resolved against a caller-supplied reference, and the per-call price/chain. It stops short of stating error behavior for unparseable input or output formatting beyond the ISO claim.

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?

Front-loaded with the core action, examples inline, and the pricing detail trailing. Nearly every clause earns its place, though the x402 price fragment reads as appended boilerplate rather than operational guidance.

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 simple two-param tool with no output schema, the description covers input intent and return format (ISO 8601). Only failure modes and timezone handling on 'ref' are left implicit.

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 the two parameters are already documented; the description reinforces that 'ref' is a caller-controlled reference moment, which mirrors the schema's 'Defaults to now'. Baseline 3 is appropriate since it adds little beyond the structured fields.

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 precise verb+resource ('parse natural-language date and time expressions into ISO 8601 dates') and anchors it with three concrete example inputs. It is unmistakably distinct from the sibling calculators_date_difference_calculator and converters_unix_timestamp_converter.

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?

Clearly signals the use case (fuzzy human phrasing → machine date) and notes a controllable reference moment, but does not explicitly say when to prefer a sibling such as live_now or calculators_date_difference_calculator. Context is evident but not routed.

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