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

Annotations already declare the mutation profile (readOnlyHint=false, destructiveHint=false, openWorldHint=false). The description adds real value beyond that with the one-hour TTL and the "fictional data" / "isolated" scoping, which tells the agent side effects are contained. It stops short of the behavior an agent most needs: whether repeated calls create multiple sandboxes, whether the sandbox expires mid-workflow, and what is returned (e.g., a sandbox identifier).

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 front-loaded sentence with zero filler, proportionate to a parameterless creation call. Every word (isolated, one-hour, fictional data) carries distinct information.

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?

For a no-argument tool with no output schema, the description should at minimum say what the caller receives back and how the one-hour window interacts with the sibling tools. Those gaps matter because this is the entry point to an entire sandbox workflow, but the core contract is present.

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?

The tool takes zero parameters, so there is no parameter meaning for the description to add; the baseline for a parameterless tool applies. The description correctly implies no inputs are required to reserve a sandbox.

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 names a specific verb and resource ("Create ... sandbox") and qualifies it with three meaningful attributes: isolated, one-hour, and fictional data. That is enough to tell it apart from the record/recall/evaluate siblings that operate inside a sandbox, though it never explicitly names any of them.

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?

There is no when-to-use guidance: nothing says this must be called before the record_*/recall/evaluate tools, whether it should be called once per session, or what to do if a sandbox already exists. The only implied usage comes from the "one-hour" lifetime.

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