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

Annotations only cover the generic safety profile (not read-only, not destructive, not idempotent, open world). The description adds real behavioral context: storage routing (CDN vs R2), public-URL side effect, the ~3MB base64 cap, and the private-storage/no-public-url mode for set_download. It does reference a `type` ("cdn"/"r2") parameter that does not exist in the schema, which muddies rather than clarifies behavior.

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?

Front-loaded with the core action and destination routing, and uses compact shorthand without filler. It is dense to the point of being cryptic in places (e.g., "provider 'r2', videoId = mediaId"), but every sentence carries information.

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?

Covers routing, the private flag, and the base64 fallback, but with no output schema the description never says what the upload returns (media id, public URL shape, failure modes), and it is silent on the required `id`/site context and the relationship to sibling upload_image. Adequate but with clear gaps for a 6-parameter tool.

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%, so the schema already documents all six parameters and the baseline is 3. The description adds routing meaning (which input maps to which storage destination) but also invents a `type` parameter absent from the schema, creating a mismatch rather than added semantic clarity.

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+resource ("Upload any plan-allowed file") and describes routing by file type, which tells the agent this is the general-purpose uploader. However, it never distinguishes itself from the sibling upload_image — it even says images go through this tool (type "cdn") — so the boundary between the two is left ambiguous.

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 parameter-level routing advice (use `fileUrl` for web files, `dataBase64` as a last resort) and notes `private` is needed for set_download, which implies usage. But it never states when to choose upload_file over upload_image or find_image, nor any prerequisites like site selection or plan restrictions beyond "plan-allowed."

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