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

Goes well past the annotations: it discloses that bodySha256 is verified before any write with a named failure mode (body_sha256_mismatch), and explains that the response sha256 is the stored blob, which can differ from submitted bytes for WebP rasters after IMAGES optimization. It also states the immediate-liveness rule (editor and draft preview now, published site at next publish), which is exactly the kind of effect an agent needs and annotations cannot express.

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 that front-load the action and scope, then layer verification and publication semantics. No filler, though the semicolon-chained second sentence packs three distinct ideas and could be split for scanability.

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?

No output schema, so the description carries return semantics and it does (sha256 of stored bytes, mismatch error). The notable remaining gap is batch failure behavior: with 1–200 items it never says whether a single bad item aborts the whole upload or writes partially, which an agent must know before committing a large batch.

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 75%, and the description supplements it meaningfully: it clarifies the key prefix rule and, more importantly, disambiguates submitted-bytes sha256 from stored-bytes sha256, a distinction the schema only hints at. It adds little for contentType or importFromUrl, keeping it short of a 5.

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?

States a specific verb and resource with scope: 'Upload 1–200 CMS assets.' The key semantics ('key = path after /assets/') and the batch limit make it instantly distinguishable from get_asset, list_assets, and delete_asset, which are the only nearby 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?

Usage is implied by the 1–200 batch bound and the CMS-asset framing, and the publish-timing sentence tells the agent why it might care. But it never states when to reach for this over another write tool (e.g. put_content), nor any precondition beyond the schema's guestToken field.

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