Update Item Metadata

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

Annotations already declare the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=false), so the bar is lower. The description adds meaningful context beyond that: it enumerates exactly which immutable/internal fields (item type, key, version, parent item, collections, tags, deletion state) cannot be touched, and notes creators are optionally replaced. This is genuinely useful boundary disclosure for a mutation 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?

Two sentences, purpose front-loaded, no filler. The second sentence's exclusion list is dense but each item earns its place by preventing invalid calls. Minor room to trim, but efficient overall.

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 no explanation, and annotations cover safety. But for a 5-parameter mutation tool with 0% schema description coverage, the missing parameter guidance leaves the definition only partially complete for correct invocation.

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?

With schema description coverage at 0% and 5 parameters including nested objects (updates, creators), the description compensates poorly. It only alludes to 'creators' being optional and to 'fields', but never explains the item_key/updates structure, the library_id/library_type scoping params, or the expected creator shape. The schema does not fill this gap on its own.

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: 'Update selected bibliographic fields and optionally replace creators.' It also draws a clear boundary by listing immutable fields. However, it never names or distinguishes itself from sibling mutation tools like update_note, update_annotation, or add_item_from_metadata, so the agent must infer which update tool applies.

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?

There is no explicit when-to-use guidance or reference to alternatives; the agent is told what cannot be changed but not when this tool is the right choice versus add_item_from_metadata or update_note. The immutable-field list is scope information rather than usage routing.

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