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

Beyond the annotations it discloses a consequential side effect not captured anywhere in structured fields: 'Confirmation makes the file publicly accessible to anyone with its media URL.' It also explains the idempotent return semantics (same mediaId on repeat) and that client dimension hints are re-measured server-side for MP4/QuickTime, which is real behavioral context rather than restatement.

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 core action and return value, then layered with side effects and exclusions. Five sentences are dense but every one carries distinct information; only the hint-measurement sentence runs slightly long.

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 mutation with real-world exposure implications and no output schema, it covers what is returned (mediaId), the idempotency contract, file-type scope, and public accessibility. The notable gap is the undocumented workspaceId parameter, which could matter for scoping the 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 0% schema description coverage the description must carry the param burden. It adds strong meaning for duration/width/height by framing them as optional client hints that may be overridden, but workspaceId (a 5th parameter, UUID) is never mentioned, leaving that parameter undocumented in both schema and description.

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 and resource ('Confirms a completed PUT upload by its fileKey') and names the outcome ('returns a mediaId for supported publishing'). It also explicitly distances itself from publish_post with 'This does not publish a social media post', so an agent can tell it apart from siblings 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?

The phrase 'completed PUT upload' makes the prerequisite step clear, and the closing sentence excludes the publish path, routing the agent elsewhere. It stops short of naming create_media_upload as the originating call, so the sequencing is strongly implied rather than stated.

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