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

Annotations already declare the safety profile (readOnly=false, destructive=false, idempotent=true), so the bar is lower, and the description still adds real behavior: replace-vs-adjust semantics per field family, and 'Every name is checked before anything is written', which discloses a validate-then-write ordering. It does not describe error handling when a name fails validation or how the 'clear' mutation interacts with concurrent edits.

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?

Five short clauses, front-loaded with the core contract ('Changes any fields... leave out what should stay') and then the field-family rules. No sentence is redundant with the name or title, and nothing is padded.

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 19-parameter mutation tool with an output schema and full annotations, the description covers the essentials: partial-update semantics, replace-vs-adjust, move semantics, clearing, and pre-write validation. The remaining gap is guidance on conflicting or redundant parameter combinations, which the schema does not resolve either.

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, and the schema already documents most individual fields. The description adds semantics the schema does not: that omitted fields are untouched (partial-update behavior) and that status/category cause a move rather than a plain value change. It does not clarify whether status and category, or labels and add_labels, can be combined.

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 and resource ('Changes any fields of one item') and pins down scope with 'leave out what should stay'. It also orients the agent relative to siblings: 'status or category moves it' explains that moves happen through this tool's fields, and 'Answers the item as get_item does' links the response shape to get_item.

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 clear operating context: omit a field to leave it unchanged, and choose labels/assignees to replace the set versus add_*/remove_* to adjust it. It does not state any when-not conditions or mutually exclusive combinations, so it stops short of full routing guidance.

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