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

Beyond the annotations, the description discloses consequential behaviors: creates a persistent sandbox receipt, debits the authorized agent test budget, and never transfers real funds. This is exactly the kind of side-effect context an agent needs and goes well beyond readOnlyHint/idempotentHint/destructiveHint.

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 description is two focused sentences, with the primary purpose first and side effects immediately after. Every sentence earns its place; there is no filler or repetition of schema details.

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 low-complexity tool with annotations and a required idempotency key, the description covers the main behavioral contract: simulation, receipt persistence, budget debit, and no real funds. It could be more complete by explaining the since parameter or the returned receipt shape, but the core calling context 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?

Schema description coverage is 0%, so the description must compensate for the undocumented parameters. It does not mention idempotency_key or since at all, leaving the agent to rely solely on parameter names and regex patterns. This is a significant gap for a tool with an obvious retry/idempotency parameter.

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 opens with a specific verb and resource: 'Simulate a Change Set purchase' for 0.05 fictitious USDC. It clearly marks the operation as a sandbox simulation, distinguishing it from real purchase tools without needing to read 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?

The sandbox and 'fictitious USDC' language clearly establish the intended testing context particular. It also states 'Never transfers real funds,' which serves as an implicit exclusion for any real-money purchase. It does not explicitly name sibling alternatives like purchase_evidence, but the context is clear enough.

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