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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the trailing 'Read-only' adds little, but the description contributes real behavioral context: newest-first ordering, one line per attempt, the empty-state string 'No payments yet.', and the failure mode of refused attempts carrying reason codes. It does not mention pagination beyond limit or rate limits, keeping it short of a 5.

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?

Well front-loaded: what it lists, then when to use it, then return shape. It is a dense single paragraph with little waste, though the trailing 'Read-only.' partly repeats the annotation and the return-field enumeration could be trimmed.

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 compensates by enumerating return fields (time, receipt id, method, URL, amount, status) and the empty-result message. For a 2-parameter read-only list tool, an agent has everything needed to call and interpret it.

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%, including range, default and pattern for both parameters, so the schema does the heavy lifting. The description only clarifies that `limit` counts lines/attempts and that ordering is newest first, which is a marginal addition over the schema text.

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 (lists) and resource (sandbox agent's most recent payment attempts) with scope and ordering (newest first), plus the three outcome categories covered. An agent can distinguish it from sandbox_pay (which makes payments) and approve (which handles holds) without opening a 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 concrete use cases — 'report what happened so far' or 'find a receipt id' — and cross-references sandbox_pay for the approval id after a hold. It stops short of an explicit exclusion (e.g. 'do not use to make or approve payments, use X instead'), but the routing intent is clear.

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