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

Annotations only cover the generic safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=false), so the description must carry the real behaviour, and it does: the URL is one-time, the flow is a client-side PUT via a returned curl command, and the widget consumes it too. It omits expiry window, auth requirements, and size limits, which keeps it from a 5.

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 fact (one-time URL) and four short, purposeful sentences. The trailing accepted-types list duplicates the schema enum, which is the only wasted line, and the fragmentary style slightly hurts parseability.

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?

With no output schema, the description usefully explains what comes back (a curl command / one-time URL) and how to consume it, and the single parameter's valid values are covered. Missing details about URL expiry, permissions, and error cases leave a small gap for a network-facing 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 description coverage is 0%, but the single parameter is an enum whose allowed values are already listed in the schema, and the description's 'Accepted: image/png, image/jpeg, image/webp' simply restates them. It adds the mild context that these describe the file being uploaded but no format/validation nuance beyond the enum.

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 opens with a specific verb and artifact: a 'One-time URL to upload a local file', which is exactly what the tool returns. It explicitly distinguishes itself from the sibling upload_images ('In chat apps prefer upload_images'), so an agent can route without opening either schema.

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 names the operating condition for this tool (clients that can run code, PUT the file with the returned curl command) and names the alternative plus the condition that selects it (chat apps → upload_images). This is explicit when/when-not routing rather than implied usage.

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