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

Annotations only cover the basic safety hints; the description goes further by explaining that the sandbox has a throwaway wallet, mock facilitator and mock APIs, that no real money moves, and that nothing outside the sandbox is reachable. It also discloses rate limits (5/min) and expiry rules (2 hours idle, 24 hours max), which the agent could not otherwise know.

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?

The core action and the call-first constraint are front-loaded in the first two sentences. Every subsequent sentence (environment nature, return contents, limits, preset examples) earns its place with 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?

With no output schema, the description correctly explains what is returned (sandbox_id, policy with budgets/allowed hosts/approval rule, paid endpoints and prices). It also covers lifecycle and rate limits, leaving nothing an agent needs in order to call and reuse the tool correctly.

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 100% and the preset enum is already fully documented in the schema, so the baseline is 3. The description nevertheless adds intent-level guidance—using 'strict' to see refusals and 'approvals' to see a payment held—which helps an agent choose a preset rather than merely pass a valid enum value.

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 resource ('Creates an isolated spendctl sandbox') and immediately names the return value (sandbox_id). It also distinguishes itself from all siblings by declaring that every other tool needs the sandbox_id, making its role as the entry point unambiguous.

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 explicit when-to-use guidance ('Call it first: every other tool needs the sandbox_id') and a precise when-to-create-another condition ('create another only to try a different preset'). No alternative is left to inference.

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