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

Annotations only mark it as a non-read-only, non-destructive, non-idempotent mutation; the description adds far more: the four required permission scopes, the fact that the first invocation is a no-op dry run, that unknown fields are rejected by name, and that the mutation only lands on the confirm_token call. This is exactly the auth/side-effect context annotations cannot carry, and it is consistent with readOnlyHint=false and destructiveHint=false.

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?

Short, front-loaded, and every sentence carries non-obvious information: purpose, scopes, call count, dry-run semantics, validation behavior, human-approval gate. No filler or restatement of the 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?

With no output schema, the description does cover the return contract of the first call (a summary plus confirm_token) and the safety model, so an agent knows how to drive it. It is incomplete only on the shape of `parts` and on the failure/abort path, which matter for a multi-step upload tool.

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 33% and the required `parts` parameter is declared as an empty object with no type, key names, or description anywhere; the description only refers to 'the same arguments' and never explains what a part is or its shape. `confirm_token` is well covered by the schema already, so the description mostly restates it. With a required, fully opaque parameter, the description should compensate and does not.

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 opening sentence names a specific verb+resource (finish a large upload) that reads as the terminal step of a start/abort multipart trio, so an agent can place it against abort_multipart_upload and start_multipart_upload without opening a schema. It never names those siblings explicitly, so the differentiation is inferred rather than stated.

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 an explicit two-call protocol with the gating condition: call once to validate, show the summary to the person, and only re-call after they agree with the same arguments plus confirm_token. That is clear when-to-use guidance. It does not say what to do if the person declines (e.g. route to abort_multipart_upload), which is the one obvious missing alternative.

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