upload_media

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

With no annotations, the description carries the burden and does well: it discloses the read-and-stream behavior, the returned media id, and the notable non-moderation/labeling policy. It doesn't cover permissions, failure modes, or side effects, but it is far beyond a bare mutation statement.

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 purpose-built sentences: one for what/why, one for mechanism and result, one for moderation policy. It is front-loaded with the key action and no sentence is wasted.

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 one-parameter tool with no output schema, the description covers the necessary call flow, return value, and important policy context. It omits format/size limits and error behavior, but these are minor for basic invocation.

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% and includes an example, so baseline is 3. The description adds meaningful constraint: path must be a local media file 'produced by your own media tool' and the bytes are streamed, which clarifies what the parameter should hold beyond the schema's generic wording.

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 uses a specific verb and resource: 'Upload a local image or video... so it can be attached to a post.' It also names the downstream consumer (post_now) and the returned media id, making the tool's role distinct among siblings.

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 connects upload_media to the post-creation workflow ('returns a media id to pass to post_now'), indicating when to use it. It doesn't explicitly state when not to use it or compare with alternatives, but the context is clear enough for an agent.

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