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

Goes well beyond the readOnlyHint/openWorldHint annotations: it explains the distinction between the two returned URLs, that download_url forces a download with a clean filename and expires after 24h, and that file_url is permanent and public. The instruction to use a temp folder and delete the file immediately is non-obvious operational policy an agent could not infer from schema or annotations.

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?

Front-loaded with the outcome (the two URLs) before the caveats, and the 24h/permanent distinction is stated compactly. The closing hygiene paragraph is slightly tangential to tool selection but carries real operational value, so it earns its place.

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 single-parameter read tool with no output schema, the description covers everything needed: what is returned, the semantics and lifetime of each URL, and how to handle the downloaded file. Nothing material is left to inference.

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?

Only one parameter and schema coverage is 100%, so the schema already documents that 'asset' accepts an id from search_assets or an exact name. The description adds nothing beyond 'an asset of the library', so the baseline of 3 applies.

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 ('Get downloadable URLs for an asset of the library') and enumerates exactly what is returned: the original file plus its thumbnail. The 'asset of the library' scoping implicitly separates it from get_post_download_url / get_my_account_post_download_url and from get_asset_preview, 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?

'e.g. to save it or send it to another service like a Drive' gives concrete usage context, and the download-to-user's-computer paragraph tells the agent how to behave in the edit/render case. It stops short of explicit when-not-to-use guidance or naming the alternative tools for preview vs. download.

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