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

Annotations already declare destructiveHint=false and idempotentHint=true, so the safety bar is lower; the description reinforces this with 'Does not delete media' and adds genuinely new behavior — that a null folderId moves items to Unfiled. It omits prerequisite details such as whether the target folder must exist or what happens to items already in that folder.

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 tight sentences with the destination rule front-loaded and the non-destructive guarantee stated up front. No filler.

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 two-parameter move operation with no output schema, the definition covers destination handling and the key non-destructive guarantee. Missing only edge-case behavior (invalid/foreign mediaIds, non-existent folderId) that an agent might reasonably want before calling.

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 0%, so the description carries the full burden, and it only covers folderId's null semantics. mediaIds gets no explanation of the UUID format, the 1–200 item bounds, or whether all IDs must be valid — those live only in 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?

States a specific verb (moves) and resource (library items) plus the target destination semantics, and distinguishes from deletion with 'Does not delete media'. Sibling disambiguation is implicit via the no-delete clause rather than naming trash_media or remove_folder directly.

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 null → Unfiled rule gives concrete usage context for folderId, but there is no explicit when-to-use/when-not guidance against siblings like trash_media, remove_folder, or rename_media. The agent must infer that moving is the non-destructive relocation path.

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