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

Beyond the annotations, the description discloses cost (free), size and duration limits, rate limit (30 per hour), return payload, PUT URL validity, and that part URLs need no API key. It also explains parallel/out-of-order uploads and replacement behavior for re-sent parts, which is exactly the operational context an agent needs.

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?

It is front-loaded with purpose, limits, return shape, and workflow, so the agent can extract key facts quickly. It is somewhat long and includes redundant part-size details plus two shell examples, but the density is largely justified by the multipart workflow.

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 complex multipart creation tool with no output schema, the description covers return fields, upload mechanics, resume behavior, completion, downstream fileId usage, and limits. Nothing essential for correct invocation or recovery appears to be missing.

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 100%, so the baseline is 3. The description adds useful semantics for sizeBytes by giving an effective 80 MB to 2048 MB operating range and repeats the partSizeBytes default/range in MB, though it does not add much for filename or contentType beyond the schema.

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 (create multipart upload) and immediately scopes it to files over 80 MB or flaky connections. That size/condition threshold distinguishes it from simpler sibling upload tools without requiring the agent to inspect other schemas.

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 clearly says when to use this tool (large files, flaky connections) and names get_upload_status and complete_upload for the resume/complete workflow. It does not explicitly name the small-file alternative such as create_upload, so the routing guidance is clear but not fully exhaustive.

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