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

With annotations already declaring destructiveHint=true and idempotentHint=false, the description adds substantial context beyond them: parts are billed until discarded, uploads newer than 24 hours are refused rather than discarded unless includeRecent is true, each entry gets its own outcome, and a non-open key is reported as failed and left untouched so a wrong id cannot read as success. It also states it cannot touch an already-existing object.

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?

Five dense sentences, front-loaded with the action and then the constraints, all of which earn their place. Slightly long, but there is no filler or repetition.

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 destructive batch tool with no output schema, the description covers the important gaps: billing implications, the recency guard and its override, and per-entry success/failure reporting. Nothing an agent needs to call it safely and interpret outcomes is missing.

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 both includeRecent and the uploads provenance are already documented in the schema, so the baseline is 3. The description goes further by explaining the rationale behind the 24-hour gate ('it may be a transfer still running') and the per-entry failure semantics, which the schema does not convey.

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 opens with a specific verb and resource ('Discards a list of unfinished uploads and the parts each holds') and the plural 'list of' distinguishes it from the singular sibling abort_multipart_upload. An agent can tell what it does and that it is the batch variant without opening the 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?

It gives a clear prerequisite workflow: name entries with the key and uploadId that list_multipart_uploads reported, and show that list to the user first. It also flags the 24-hour refusal and the includeRecent override. It stops short of naming abort_multipart_upload as the single-upload alternative, so no explicit when-not guidance.

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