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

Annotations already declare destructiveHint=true and idempotentHint=true, so the safety profile is known. The description adds useful format behavior (year-only values preserved rather than normalized to January 1st) but never warns that setting a date overwrites existing values or what happens to fields left out of the call — the main destructive risk an agent needs flagged.

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 tight sentences with the affected fields front-loaded and the format/clear semantics immediately after. No filler and nothing buried.

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 6-parameter mutation tool with no output schema, the description covers the fields, accepted formats, and clearing behavior well. The remaining gap is what a call does to dates not mentioned in it and how item identification resolves between title and item_id, which leaves slight ambiguity about the write's scope.

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 baseline is 3, but the description adds genuine meaning beyond the schema: it restates the accepted formats in one place and clarifies the non-obvious semantic that a year-only finish stays a year rather than becoming January 1st. Minor gap: it says nothing about title vs item_id selection, though the schema covers that.

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 (set or clear), a specific resource (dates on one library item), and enumerates the three fields affected. An agent can distinguish it from siblings like set_progress, set_format, or update_status without reading any 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 two explicit use cases: imported histories that only carry years, and correcting a wrong date. That is clear positive guidance but it never names an alternative tool (e.g., set_progress for current reading position) or states when not to use it.

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