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

Annotations only provide low-level hints, so the description carries the disclosure burden. It meaningfully adds that the grant is short-lived, that upload requires POSTing raw bytes with returned headers, and that images are AI-moderated before going live. It stops short of describing expiry details or failure behavior, but it is substantially transparent.

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 dense sentences with no filler: purpose, usage protocol with returned fields, and a behavioral caveat. The most important information is front-loaded and the rest is directly actionable.

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 two-parameter tool with an output schema, this description is complete enough to invoke correctly: when to call it, what it returns, how to perform the upload, how to integrate with create_listing, and what moderation behavior to expect. The only minor omission, an explicit pointer to the existing-listing flow, is already covered by the clear 'about to publish' framing.

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 should compensate for the two required parameters. It does not explain how content_type and file_size are used, whether they must match the uploaded bytes, or how they affect the grant. The indirect mention of raw image bytes is not enough to replace missing parameter guidance.

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 and resource: getting a short-lived upload grant to attach a photo to a listing. It also distinguishes itself from siblings like create_listing and update_listing_images by describing the grant-and-upload flow rather than the listing-creation or image-update flow.

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 clearly frames when to use it: before publishing a listing, for any vertical/role, and it tells the agent to pass the returned key into create_listing's images array. It does not explicitly mention update_listing_images for existing listings, so alternative routing is left somewhat implied.

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