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

Annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false, so the safety profile is covered structurally. The description adds the meaningful precondition that the destination folder must be owned by the caller, plus an endpoint mapping, but says nothing about partial failure, overwrite semantics, or the effect on source folders.

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 compact sentences with the core operation and its key constraint front-loaded; nothing is padded or repeated for 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 mutation tool whose annotations carry the safety profile and whose schema fully documents inputs, the definition is essentially sufficient. It leaves only minor operational details (partial-failure behavior, whether files are removed from their previous folder) unstated, and there is no output schema to explain.

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 100%, so both parameters are fully documented in the schema, including the root default and the maxItems=100 constraint. The description restates the same 'up to 100' and 'folder_id omitted' facts rather than adding new meaning, so the baseline 3 applies.

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 and resource ('move media files') plus scope constraints: the 100-file cap and the root-vs-folder destination behavior. No sibling tool performs a move, so the definition is unambiguously distinct without needing to name an alternative.

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 'or to the library root when folder_id is omitted' clause tells the agent which destination applies, which implies when to use it. However, there is no explicit when-not guidance, no mention of prerequisites beyond ownership, and no comparison to sibling tools like update_media or create_folder.

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