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

Annotations only declare readOnlyHint=false and destructiveHint=false, so the description adds real value: content-addressed deduplication via sha256, the mandatory PUT even when the object already exists, and the privacy-until-referenced visibility rule. It still doesn't say how long 'status until available' may take, what the terminal status values are, or whether an abandoned upload session expires.

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?

Extremely dense — arrow-chain notation with no filler sentences, and the exception about the mandatory PUT is placed immediately after the step it modifies. The tradeoff is that it opens mid-protocol rather than with a leading statement of what the tool does, which the title has to carry.

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 and 7 parameters, the description does reveal the initiate response shape (put.url, put.headers, upload_id) but leaves the complete and status responses opaque — 'status until available' never enumerates the possible state values or the polling cadence. For a stateful, multi-call workflow tool this is the main remaining gap.

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 description coverage is only 14% (just idempotency_key), so the description must compensate. It does map the key parameters to actions (initiate = filename/bytes/sha256, complete/status = upload_id), which is genuinely useful, but declared_mime is undocumented in both the schema and the description, and the description never confirms which params belong to which action exhaustively.

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 lays out a concrete multi-step upload protocol (initiate → PUT → complete → status) with named resources (put.url, put.headers, upload_id), which is far more specific than the generic name 'upload'. It doesn't explicitly differentiate itself from any sibling tool, but among the listed siblings none competes for this job, so the ambiguity cost is low.

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 ordered procedure and one important exception ('required even when deduplicated: it proves possession'), plus the downstream condition for the file becoming visible ('Private until referenced'). What's missing is any statement of when to prefer this over other ways of attaching content, or what to do on failure/retry beyond the schema's idempotency_key.

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