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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuinely useful behavior beyond that: this tool renders a UI panel rather than returning data, it orders results newest-first, and it is scoped to the library panel's call site.

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 with the resource and browsing purpose front-loaded; the slightly awkward 'on a page of its own' phrasing costs a little but there is no padding.

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 no-output-schema, zero-required-param UI opener, the definition covers what the agent needs: what opens, the ordering, and the call context. Only the return behavior (that no data payload is produced) is left implicit.

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%: the kind enum and the limit default/max are fully documented in the schema itself. The description only reinforces the already-stated 'newest first' ordering, adding little beyond the schema.

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 names a specific resource (the account's media library) and states what happens (opens it as its own browsable page, newest first). It does not explicitly contrast with the sibling list_assets, so an agent must infer the difference, but the core verb+resource is clear.

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 gives invocation context ('Opened from ChatGPT's sidebar or beside a conversation; only the library panel calls it'), which implies when it is used, but it never states when NOT to use it versus list_assets or import_media. Usage is implied rather than spelled out.

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