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

Annotations already declare readOnly, idempotent, and non-destructive hints, but the description adds valuable behavioral details beyond that: the ordering ('newest first'), the fact that returned URLs are directly accepted by assemble_video and edit_asset, the caveat about user-attached files not being present until import_media, and the mechanism of panel picks reaching the agent as context with position numbers and URLs. No contradiction with annotations; it enriches them.

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 longer than a minimal phrasing, but every sentence contributes unique value: purpose, ordering, URL compatibility, import caveat, panel pick behavior, and application instruction. It is front-loaded with the core purpose and maintains clear logical flow. A slight trim could make it tighter, but it does not waste words.

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 read-only listing tool with no output schema, the description covers all essential aspects: what is listed, ordering, how URLs are used by other tools, when assets appear, how panel picks are presented, and instructions to apply them precisely. The schema covers param constraints, and annotations cover safety. Nothing an agent needs to call this correctly is missing.

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 provides 100% descriptive coverage for all three parameters (kind, limit, query) with clear enums and descriptions. The description does not add new semantics about the parameters themselves beyond reinforcing the 'newest first' ordering for limit. Baseline 3 is appropriate since the schema already does the heavy lifting.

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 ('Browse') and a clear resource ('the account's media library') with explicit scope ('every image, video, and audio file'). It names the result ordering ('newest first') and directly ties the returned URLs to sibling tools ('the ones assemble_video and edit_asset accept'), which clearly distinguishes it from those siblings. This is a precise, actionable purpose.

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 description gives explicit when-to-use guidance: 'start here when asked to cut, caption, score, or otherwise finish media the account already has.' It also contrasts with import_media by noting that user-attached files are not listed until imported. It explains the panel-pick flow and instructs how to apply picks ('exactly those files, and do not assume picks mean joining them'). This fully informs an agent when to call this tool and when not to.

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