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

Although annotations include openWorldHint and no destructive hint, the description reveals the critical behavioral truth: this is a no-op placeholder that only records the request and returns a notice. This goes well beyond what the annotations convey and prevents false expectations.

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 compact sentences, with the most important caveat ('Not available yet') front-loaded. Every sentence contributes essential guidance and there is no filler.

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 beta stub with two optional parameters< no output schema, and clear annotations, the description fully covers behavior, expectations, and the correct alternative. An agent has enough context to avoid misleading the user.

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?

The schema already fully documents both parameters with 100% coverageikuha, so the description need not repeat them. It indirectly implies the parameters will not produce a thumbnail, but it does not add per-parameter details beyond 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?

The first sentence immediately states this tool is unavailable and that finished videos already have thumbnails via kleo_get_result. The description also clarifies that calling it only records the request and returns a notice, so an agent understands this is a stub rather than the generation tool its title implies.

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?

It explicitly warns not to promise extra thumbnails and directs users to kleo_get_result for the existing thumbnail. This gives clear when-to-use and when-not-to-use guidance, plus a named alternative sibling.

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