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

The description reveals side effects and failure modes beyond the generic annotations: it verifies object existence, records real size and checksum, rejects oversized uploads, and makes the memory findable/downloadable. This is meaningful behavioral detail an agent cannot infer from readOnlyHint/destructiveHint alone.

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?

The core action is front-loaded, and every sentence contributes a necessary piece of information: precondition, behavior, source of id, and return shape. There is no filler or restating of title.

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 single-parameter finalization step, the description covers enough of the workflow, side effects, validation, and return value. Since an output schema exists, the described return shape is a useful addition rather than redundant, and all essential agent guidance is present.

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?

The schema only contains an unannotated string parameter id, so the description's note that id comes from create_upload is crucial. It tells the agent where to get the value and how it relates to the upload flow; a little more format detail would be nice, but it is adequate for one parameter.

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 begins with a specific verb and resource ('Confirm a media upload') and includes a precondition ('after you've PUT the bytes'). It then details what the confirmation does — verifying existence, recording size and checksum, and making the memory findable/downloadable — which clearly separates it from siblings like create_upload.

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 explicit workflow guidance: call this only after PUTing the bytes, and use the id returned from create_upload. It does not name alternatives because the sequencing itself is sufficient to disambiguate, though there are no explicit exclusions.

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