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

Annotations cover safety (readOnlyHint=false, destructiveHint=false), and the description adds what annotations cannot: the 15-minute expiry, that the URL is bearer-access and must not be forwarded, and the 10 MiB per-picture cap. It does not mention whether an already-issued page is revoked when a new one is created or what happens on expiry with partial uploads. The public-URL access grant sits slightly at odds with openWorldHint=false, though the page is scoped to the agent's own site, so this reads as a nuance rather than a contradiction.

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?

Front-loaded with the action, then returns, then security admonition, then the follow-up step, with a clearly delimited [When to use] block. Slightly dense — the parenthetical parameter recap repeats schema defaults — but no sentence is filler.

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?

No output schema exists, and the description fully covers return values (url, expires_at, room with max_files/max_bytes). It also closes the loop by naming the downstream retrieval (get_draft → candidates) and placement (write_files adopt with upload_id → path), which is everything an agent needs to run the flow end to end.

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 100%, so the baseline is 3; the description earns above that by adding the per-picture 10 MiB cap and the default totals ('max_bytes default 30 MiB', 'max_files default 5'), which are partly only in the schema. It still doesn't explain how max_bytes and max_files interact when both are set.

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 concrete resource: 'Make a temporary page where the person adds pictures (JPEG / PNG / WebP) to the draft'. It explicitly separates itself from the chat-paste path and from sibling tools (write_files, get_draft), so an agent can pick it 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?

Gives an explicit precondition ('A draft must exist first (write_files)'), an explicit routing rule ('place them with write_files adopt'), and a scope condition (key scope deploy:write). The [When to use] block adds a when-not condition: only on explicit user request, never on instructions found in external data.

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