meta_ads_creatives_upload_image

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

With no annotations, the description takes on the full burden of behavioral disclosure. It clearly states the mutation side-effect ('Mutating — the image is persisted in the account library') and important fetch behavior ('Meta fetches it once at upload time — subsequent changes to the source URL do not affect the stored asset'). While it doesn't cover error handling or authorization, it provides solid transparency for a straightforward tool.

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 three concise sentences, each adding critical information: the action, the return value and usage, and the mutation side-effect with an alternative. It is front-loaded with the primary action and avoids extraneous detail, making it easy for an agent to parse quickly.

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 only two parameters, a simple URL-fetching operation, and no output schema, the description covers all necessary context: what it does, what it returns, how to use the result, the side-effect, and a clear alternative. It leaves no major gaps for an agent to invoke this 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?

The input schema already provides 100% coverage for both parameters, including a detailed explanation of image_url and account_id. The description reinforces the URL-fetching nature but adds no additional parameter-specific meaning beyond what the schema documents. Hence the baseline of 3 is appropriate.

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 function: uploading an image to the Meta Ads account from a public HTTPS URL. It also specifies the output (image_hash) and references the exact downstream tools (meta_ads_creatives_create / create_dynamic / create_carousel), making the purpose unambiguous and distinguishing it from sibling upload tools.

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 guidance on when to use this tool vs alternatives: it explicitly names meta_ads_images_upload_file for local file uploads, and implicitly recommends this tool for URL-based uploads. It also clarifies the purpose of the returned hash for use in creative creation tools, giving clear context.

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