Upload a creative as raw bytes (100 MB max, Content-Length); 200 if duplicate

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

Beyond the annotations (readOnlyHint=false, openWorldHint=true), the description discloses that the call is gated on confirm, that there is no server-side dry run, the 100 MB/Content-Length transport constraint, and that a duplicate returns 200 rather than erroring. These are real behavioral facts an agent needs. It stops short of saying what the preview response contains or what happens on non-duplicate conflicts.

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 dense sentences with the operation, constraints, and endpoint front-loaded and no filler. The telegraphic semicolon style is compact and readable, though the interleaving of format, limits, and status codes makes it slightly scannable-hostile.

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 six-parameter binary upload mutation with no output schema, the description covers the critical items: size limit, transport framing, the confirm gate, no dry run, and duplicate handling. Missing only secondary detail such as accepted content types and what the preview payload looks like.

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 67% and the description only reinforces the confirm gate, which the schema already explains. The meaning of name, tags, clientId, and idempotencyKey is left entirely to the schema, so the description adds little parameter-level meaning beyond the baseline.

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 ('Upload a creative as raw bytes') plus the wire format (raw bytes, Content-Length) and the endpoint path, which is concrete. It does not distinguish itself from nearby siblings like creativeLibrary_file or creatives_upload, so an agent cannot tell from the description alone which upload path applies.

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 gives an important execution condition ('not executed unless confirm: true') and notes there is no server-side dry run, which implies the preview-then-execute pattern. It offers no guidance on when to pick this tool over creativeLibrary_file or creatives_upload, so sibling 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.