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

Annotations already establish that this is a non-read-only, non-destructive, non-idempotent operation. The description adds meaningful behavior beyond that: it verifies the file arrived, records its size and type, and reports when the file is missing. It does not discuss auth requirements or the consequences of repeat calls, but annotations cover the idempotency profile.

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, front-loaded with the trigger condition and followed by the verification/recording behavior. There is no filler or redundancy.

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 one-parameter upload-completion tool with annotations and no output schema, the description covers when to call it, what it checks, and what happens if the file is not present. Nothing needed to invoke it correctly is missing.

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?

There is only one parameter and schema coverage is 100%; the schema already documents that mediaId comes from create_presigned_upload_url. The description supplies sequencing context but adds no syntax, format, or validation detail for mediaId beyond the schema, so the baseline 3 is appropriate.

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?

It states a specific verb and resource: complete an upload after PUTting to the presigned uploadUrl, then check arrival and record size/type. The reference to the presigned uploadUrl distinguishes it from create_presigned_upload_url and implicitly from upload_media_from_url by framing it as the post-PUT completion step.

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 trigger is explicit: "Call after PUTting a file to the presigned uploadUrl." It also explains the not-yet-present case ("Says so if the file is not there yet"). It does not name alternative tools or state when-not to use it, so it falls 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.