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

With no annotations, the description carries the full transparency burden. It discloses content-based deduplication (returns existing file), a 100 MB size limit, and multipart/form-data encoding—specific behavioral traits that meaningfully affect invocation and expectations, going beyond the schema.

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 concise sentences, each earning its place: purpose, key behavioral trait, and input constraint. The description is front-loaded and highly scannable, with no redundant wording.

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 is simple, and the description covers purpose, dedup, size, and input constraints. However, with no output schema, it does not explain what the call returns on success (e.g., file ID or URL), leaving a minor but relevant gap for an upload operation.

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 provides 100% coverage of all parameters, including their roles and mutual exclusivity. The description adds the 'exactly one source' rule but no additional semantic depth; hence the schema 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 uploads a file via multipart/form-data and provides a concrete use case (image for variant/collection). This distinguishes it from the sibling upload_video tool and clearly communicates the action and resource.

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 offers context for when to use the tool ('e.g. an image for a variant or collection') and enforces the 'exactly one source' rule. It does not explicitly name alternatives or exclusions, but the context and dedup behavior make the usage scenario clear.

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