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

With no annotations, the description must carry the full behavioral burden. It usefully discloses the base64 transport, the 50 MB ceiling, the browser fallback, and the returned assetId, but says nothing about permissions/project access, whether existing assets are overwritten, transcoding/processing latency, or failure modes for a rejected mimeType.

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?

Three short sentences, front-loaded with the action, then the payload format and size limit, then the return value. Nothing is redundant or buried.

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 write tool with no annotations and no output schema, the description supplies the essentials: what it creates, how to pass the payload, the hard size limit with an escape hatch, and what comes back. The remaining gap is enforcement behavior (errors, overwrites, permissions) rather than anything needed to form the call.

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%, so all four parameters rely on the description. It clarifies contentBase64 as file bytes encoded in base64 with a size cap, and implies the media types allowed for mimeType, but filename and projectId receive no explanation and no example payload is given.

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?

Names a specific verb and resource ('Upload a video, audio or image file into a project's media library') and states the return value (assetId). The action is clearly distinct from read-oriented siblings such as asset.get, asset.list and asset.capture_frame, though no sibling is named explicitly.

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?

Gives a concrete when-not rule: files over 50 MB cannot go through this tool and must be uploaded in the browser. That is a real routing constraint an agent cannot infer elsewhere. It does not say how this relates to asset.capture_frame or asset.replace_placeholder for building an asset library.

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