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

Annotations already declare non-read-only, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds genuinely new behavioral context: it is the finalization step of a two-phase upload and depends on prior byte transfer. It does not say what happens if called before the PUT (error vs. empty file), which is the main remaining gap.

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 sentences, front-loaded with the verb and the prerequisite, with no filler. Every clause carries either sequencing information or result-usage guidance.

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?

An output schema exists and annotations are rich, so the description only needs workflow context — which it supplies. Failure modes (calling before the PUT, expired presigned URL, mismatched key) are not covered, which is the one substantive omission for a stateful finalization step.

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 the single `key` parameter is already documented as coming from file.request_upload after the PUT; the description only restates that sequence rather than adding format, encoding, or validation detail.

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 (finish/confirm a file upload) and ties it to the exact preceding sibling step `file.request_upload`, so it is unambiguously distinguishable from request_upload and from ordinary read/write item tools.

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?

Gives the precise precondition — call only after the bytes have been PUT to the presigned URL — and names the prerequisite tool explicitly, so the two-step workflow is fully specified. It also tells the agent what to do with the result (File List field or Cover).

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