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

Annotations only indicate readOnlyHint=false, destructiveHint=false, and openWorldHint=true, so the description carries the burden of behavioral disclosure. It adds meaningful detail: SocialRobot fetches the bytes, stores them, and returns a permanent URL. The 50MB limit further clarifies expected constraints, which goes beyond what annotations provide.

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 compact and front-loaded, with the fallback context appearing first. Each sentence earns its place: fallback condition, input options, behavior, alternative preference, and size constraint. There is slight redundancy between the first sentence and 'Prefer get_media_upload_url when you can PUT,' but overall it is efficient and scannable.

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 tool with no required parameters, no output schema, and sparse schema descriptions, the description provides the essential operational picture: when to use it, what inputs are acceptable, what happens during execution, and what the return value is for. It does not explicitly state whether file and sourceUrl are mutually exclusive or what happens if both are provided, but the intended workflow is clear enough for an agent to use it 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 description coverage is 0%, but the description adds meaning for two of the four parameters: 'file' as a ChatGPT file and 'sourceUrl' as a public https URL. However, 'filename' and 'contentType' remain unexplained, and the description does not clarify the relationship or precedence between them. It partially compensates for the schema gap but leaves room for ambiguity.

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 clearly states the tool's role as a fallback media upload mechanism, explicitly distinguishes it from get_media_upload_url, and names the concrete outcome: returning a permanent URL for create_post. It uses a specific verb ('upload') and identifies the resource ('media'), making the tool's purpose immediately obvious.

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?

The description provides explicit when-to-use and when-not-to-use guidance: use this tool when you cannot PUT to the presigned URL, and prefer get_media_upload_url when PUT is possible. It also specifies allowed input modes ('ChatGPT file' vs 'public https sourceUrl') and the 50MB limit, giving an agent enough context to select and invoke the tool correctly.

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