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

With all annotations false, the description carries full behavioral disclosure. It reveals that the tool returns presigned URLs, that the agent must upload bytes itself, and that a subsequent upload_finish call is required. It also explains kind and role options. This is substantive behavioral context beyond the schema.

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 sentences with zero filler. The first sentence states the purpose and the presigned-URL flow; the second clarifies kind and role. Front-loaded and efficient.

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-phase upload initiation, the description covers the essential workflow, return behavior, and kind/role semantics. It does not mention error conditions or prerequisites (e.g., that the project must already exist), but given sibling tools like create_project and no output schema, it provides sufficient context for correct invocation.

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 67%, so the description compensates for the undocumented 'kind' parameter by explaining each enum value ('original', 'clip', 'music', 'image') and the conditional 'role' ('shorts_reference'). This adds meaning beyond the schema for the most semantically rich parameters. Other parameters (filename, size_bytes, duration_s) have schema descriptions.

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 clearly states the action ('Begin uploading'), the resource ('LOCAL file into an explicit project'), and the multi-step flow (returns presigned URLs, upload, call upload_finish). It also explains kind and role semantics, distinguishing this tool from upload_finish and other upload-related siblings.

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 description explains the two-step workflow (get presigned URLs, upload, then call upload_finish) and explicitly notes 'LOCAL file' to set scope. However, it does not explicitly name alternatives for remote uploads (e.g., fetch_url or download_url), so the 'when not to use' guidance is implied rather than stated.

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