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

Annotations already indicate this is a write operation (readOnlyHint=false) and non-destructive (destructiveHint=false). The description adds only that the item must exist, but fails to disclose key behavioral nuances such as whether the update is partial (only provided fields changed) or full (omitted fields cleared), or how errors like non-existent IDs are handled. With no output schema, this gap is significant.

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?

The description is a single, concise sentence containing only essential information. It is front-loaded with the verb 'Update' and the resource, with zero fluff. Every word contributes to conveying the tool's purpose.

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?

With 10 parameters, many optional, and no output schema, this tool is moderately complex. The description is too sparse to be fully complete. It does not mention that this is likely a partial update (given all fields except id are optional), what the return value looks like, or how to handle cases where the item doesn't exist. Sibling tools like create_library_item and delete_library_item exist but the description does not clarify usage boundaries.

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?

The input schema has 100% coverage, with each parameter having its own description. The tool description does not add any additional parameter-level meaning, so the baseline score of 3 is appropriate. It does not clarify relationships between parameters (e.g., whether evergreenEnabled and evergreenIntervalDays are dependent) but that's not required for this dimension.

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 clearly states the action ('Update') and the resource ('an existing content library item'), which is specific and distinguishes it from sibling tools like create_library_item, delete_library_item, and get_library_item. The 'existing' qualifier reinforces that it modifies an already-created 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?

The phrase 'existing content library item' implies it is used when you need to modify an item that already exists, providing basic usage context. However, it does not explicitly state when not to use it, mention alternatives (e.g., create_library_item for new items), or outline any prerequisites beyond the item existing.

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