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

The description meaningfully adds to the single readOnlyHint=false annotation by disclosing the confirm-gated preview behavior: execution only occurs with confirm: true. It also clarifies visibility implications for clients, though it does not describe required permissions or preview contents.

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 three tight sentences with no wasted wording. The core action and audience purpose are front-loaded, followed by source options and the important confirm gate.

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 create tool with a nested audience object, no output schema, and minimal annotations, the description covers the essential behavior: what is created, how content is supplied, who can see it, and that execution is confirm-gated. It is complete enough to invoke correctly, with only optional metadata fields left to the schema.

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 50%, and the description reinforces the key link-or-fileKey choice and confirmation flag. However, it largely repeats schema-level information and does not add much meaning for title, category, fileName, mimeType, description, or the nested audience 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?

The description states a specific verb and resource: adding a document to the coach's library. It also clarifies the visibility-selection aspect and distinguishes itself from sibling library tools such as list_library_items, update_library_item, and delete_library_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?

It explains the two supported source modes, a link or a fileKey from upload_file, and notes that the item will appear for clients at Me → Library. The context is clear, though it does not explicitly say when to use update_library_item instead of creating a new item.

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