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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the description doesn't need to repeat that. It adds value by disclosing failure modes (network restrictions, host_not_allowed) and prescribing fallback behavior (use File Upload Widget, no retry). This is behavioral context beyond the annotations, though not exhaustive about internal details.

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, each earning its place. The first states the tool's purpose and accepted file types; the second gives precise usage directives and fallback rules. No superfluous words, and the critical information is front-loaded.

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?

The tool has an output schema, so the description needn't explain return value structure. It covers what the tool returns, supported file types, when to use it, and what to do on failure. For a single-parameter informational tool, this is fully sufficient and leaves no obvious gaps for an agent.

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 only parameter, task_type, is fully described in the schema with an enum of 65 values and a clear description. The tool description does not add extra semantics beyond what the schema already provides, but since schema coverage is 100%, 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 explicitly states the tool returns the upload API endpoint and example request/response for images (JPEG, PNG) or videos (MP4). It clearly distinguishes itself from siblings like upload_file or File-Upload by focusing on retrieving API information rather than performing an 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?

It provides explicit when-to-use guidance ('Use when the user wants to upload an image/video via the API') and equally explicit failure conditions ('If upload cannot be completed... do not retry. Immediately use the File Upload Widget instead'). It also instructs not to ask for a public URL, removing ambiguity. This is model guidance.

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