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

The description adds substantial behavior beyond the annotations: upload must use the returned uploadUrl and ALL uploadHeaders with no API key, followed by company_complete_media. It also explains lost-response retry semantics and the idempotencyKey requirement, consistent with idempotentHint=true and destructiveHint=false.

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?

The description is dense but front-loaded and every sentence carries operational value: reservation purpose, upload mechanics, completion step, thumbnail constraints, and retry behavior. There is no redundant restatement of the name or schema.

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 mutation tool with no output schema and partial schema descriptions, the description covers the critical workflow, upload headers, completion step, thumbnail constraints, and response-loss retry behavior. It leaves some general parameter and response details unspecified, but is largely sufficient to invoke the tool correctly.

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 only 38%, but the description compensates for several key fields by specifying purpose=youtube_thumbnail, type=image, JPEG/PNG, size and dimension constraints, and Company IDs only. It still does not explain fileName or fully document general type/contentType/size behavior outside the thumbnail case.

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: 'Reserve an upload for an existing Agency draft.' It also distinguishes the reservation step from the follow-up company_complete_media call and clarifies the YouTube thumbnail use case.

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 gives clear usage context: reserve for an existing Agency draft, then PUT bytes and call company_complete_media. The YouTube thumbnail path is explained well, but there are no explicit exclusions or direct comparison to alternatives such as get_upload_url or attach_media.

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