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

Beyond the annotations (which only declare the read/write/idempotency profile), the description discloses the two-phase workflow, that bytes must not be passed through arguments, retry-forbidden failure modes (proxy 403, connect_rejected, DNS failure), and what the call returns (Asset ID and upload commands). This is rich behavioral context the structured fields do not carry.

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?

Front-loaded with the action and accepted inputs, then workflow, then failure handling, then the alternative tool. Dense but every sentence earns its place; the parenthetical file-extension lists are long but load-bearing for input selection.

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?

There is no output schema, and the description compensates by naming the return values (Asset ID plus commands) and the follow-up step. For a 7-parameter, multi-step upload tool it is substantially complete, though it does not explain why video-range parameters are required alongside a generic file upload.

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?

With 57% schema coverage, the description must partly compensate, and it does by tying inputs to file classes ('Supply filename, MIME type and byte size') and stating the type-specific size ceilings (2 MB data, 10 MB font). It does not add meaning for the video-range params, but the schema already describes startSeconds/endSeconds/keepOriginal/projectId.

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?

States a specific verb+resource ('Begin uploading a local media file, a data file, or a font file') and enumerates the accepted file classes with size limits. It explicitly names its downstream sibling complete_asset_upload and the alternative upload_files, so an agent can tell it apart without opening a schema.

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?

Gives explicit sequencing ('run them... in order, then call complete_asset_upload') and a clear alternative rule ('If you have the upload_files tool, call it instead'), plus when-not guidance for failed connections ('do not retry it'). Nothing about selection is left to inference.

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