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

Annotations already establish read-only/idempotent/non-destructive behavior, and the description adds important non-obvious behavioral detail: budgets carry their own currency, amounts are NOT converted to USD base, and spend/projected values are denominated in status_currency. The warning never to quote figures as dollars without checking those fields is exactly the kind of behavioral caveat that protects an agent from downstream errors.

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 front-loaded with the main action and only adds necessary details: the mirrored endpoint and the critical currency semantics. Every sentence earns its place, and the warning is concise yet highly actionable. It is dense but not bloated.

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 zero-parameter read-only list tool with no output schema, the description covers the core return fields, status notions, and the crucial currency pitfall. It does not spell out the exact response container or pagination, but given the simple list nature and the endpoint mirror, the information is sufficient for correct invocation in most cases.

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 has zero parameters, so the baseline is 4 and there is no parameter burden to compensate for. The description still adds relevant context by implying the account is fixed ('this account') and mirroring GET /api/accounts/:accountId/budgets, which clarifies how the account is scoped even though no explicit parameter exists.

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 uses a specific verb and resource: 'List this account's spend budgets' and further specifies the payload (current-cycle status, spend, projected total, states). It clearly separates itself from sibling tools by naming the exact domain: budgets with currency semantics distinct from cost tools.

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 description gives a clear context for when this tool is appropriate: listing this account's spend budgets with their current-cycle status. It also indirectly contrasts with 'cost tools' by warning that budget currencies are not converted to USD, which helps an agent avoid misusing this tool for dollar-normalized cost queries. It does not explicitly enumerate sibling alternatives or exclusion conditions.

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