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

Annotations already declare readOnlyHint=false, destructiveHint=false, and openWorldHint=false, so the mutation/safety profile is covered. The description adds the workflow role of a folder (a container for later uploads/moves), but says nothing about permissions, whether folders are renameable/removable, or naming constraints. Useful but modest context on top of the annotations.

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 tightly packed sentences with zero filler: the purpose is front-loaded and the second sentence carries only actionable workflow routing. Every clause earns its place.

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 simple two-parameter create tool with full annotation coverage and no output schema, the description supplies enough to call it correctly and to know what to do next. Minor omissions (permissions, whether the folder name must be unique) are non-blocking.

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%, and the schema already documents both 'name' and 'parent_id' including the nesting behavior and the list_folders source. The description's example ('win-graphics') merely echoes the schema's own example, adding no syntax or constraint detail beyond it. Baseline 3 is appropriate when the schema 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 and resource ('Create a media-library folder'), which is clearly distinct from sibling create_* tools that operate on posts, hashtags, and webhooks. It does not explicitly contrast itself against those siblings, but the resource noun makes the target unambiguous.

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 concrete usage context ('Use it to organize assets') and routes the agent to the correct follow-up tools: upload_media (folder) for uploads and update_media (folder_id) for moving files. There is no explicit when-not-to-use guidance or prerequisite/permission note, so it stops short of a 5.

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