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

Annotations already declare the safety profile (readOnlyHint=false, idempotentHint=false, destructiveHint=false, openWorldHint=true). The description adds real behavioral context beyond that: the 2 GB size cap, the https/downloadability constraint on the source, and the fact that it fans out into one tracked link per recipient. It does not mention auth requirements or failure handling, so it stops short of the top tier.

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?

Two sentences, zero filler. The primary action and its constraints are front-loaded, and the sibling redirect is the final clause where an agent needs it.

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 multi-effect tool (upload, create, distribute) with no output schema, the description conveys enough: source requirements, size limit, and the link-per-recipient outcome. Missing only edge behavior such as failure/partial-success handling, which would push it higher.

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 50%, so the description must carry weight and largely does: it clarifies that url must be https and downloadable, that duration is needed 'unless Alto can measure the file,' and that recipients each get a tracked link. It leaves slug, description, and title unelaborated, but those are conventional and partly covered by the schema.

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?

Specific verb and resource (upload a finished video) plus precise scope: it must already be online as an https URL Alto can download, up to 2 GB. It also names the side effect (creates the video and one tracked link per recipient) and distinguishes itself from create_upload.

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?

Explicitly states the condition that selects this tool (a finished video already hosted online) and names the alternative for the other case: 'For a file on your machine, use create_upload.' When-to-use, when-not, and alternative are all present.

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