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

Annotations already declare idempotentHint=true, readOnlyHint=false and destructiveHint=false, so the safety/idempotency profile is partly covered. The description adds genuinely new behavioral context: the job is asynchronous and follows a 202-then-poll lifecycle, and it has no side effects on real auctions, ads or money — the latter is important for a non-readOnly tool. It does not mention auth requirements or rate limits.

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?

A single sentence, front-loaded with the core action and scope, with the polling follow-up appended. No filler or repetition 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?

An output schema exists, so return values need not be explained; the description still covers the async 202-then-poll behavior and names the tool used to retrieve results. For a one-parameter sandbox tool this is fully sufficient.

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?

Only one parameter and schema description coverage is 100%, so the schema already fully documents idempotencyKey (client-chosen, same key returns same jobId). The description references the Idempotency-Key pattern but adds no syntax, format, or edge-case detail beyond the schema, so the baseline 3 applies.

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+resource (start a synthetic asynchronous sandbox job) and immediately scopes it as exercising the Idempotency-Key / 202-then-poll pattern without touching real auctions, ads or money. It names the sibling get_sandbox_job as the polling counterpart, so an agent can distinguish it from siblings without opening any 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 clear context for use (synthetic job to exercise the write API's async idempotency pattern safely) and explicitly routes the follow-up action to get_sandbox_job. It stops short of stating exclusions, e.g. when a real (non-sandbox) job creation path would be preferred, but no such sibling exists here.

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