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

Annotations already disclose the safety profile (write, non-destructive, non-idempotent, closed-world), so the burden is lower. The description usefully adds two behavioral constraints beyond them: the image must be 'owned' and 'still' (i.e., no animation). It still omits what a non-idempotent upload does on duplicate content and what the call returns.

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?

A single front-loaded sentence with no filler; every clause (owned, still, formats, reuse) 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?

For an upload tool with 0% schema coverage and no output schema, the description should explain the return value (presumably an asset identifier needed for later reuse) and the encoding/size expectations of the base64 payload. Neither is present, leaving real gaps for an agent trying to call it correctly.

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 the description must carry parameter meaning and largely does not. It enumerates PNG/JPEG/WebP, which effectively restates the media_type enum, but says nothing about the base64 parameter, its encoding, or the ~14MB size bound already implied by maxLength.

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 states a specific verb (upload) and resource (image asset) plus constraints on what qualifies: owned, still, and the accepted formats. It is clearly understandable, but it never distinguishes itself from siblings such as set_brand_asset, get_image_asset, or create_image_pack, so an agent must infer the boundary.

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 phrase 'for reuse in templates' hints at intent, but there is no explicit when-to-use guidance, no exclusion of alternatives like create_ai_image or set_brand_asset, and no stated prerequisites such as prior ownership or account state.

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