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

Annotations already cover the read-only/idempotent/non-destructive profile, so the description clears the lower bar easily. It adds substantial context beyond them: the meaning of projected_cents (trend-based, weekday/weekend aware, not a run rate), the two distinct currency fields, and a concrete warning not to quote figures as dollars without checking currency fields.

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?

Front-loaded with the core purpose and status fields in the first sentence, then details. The middle sentences on projected_cents and currency are dense but each earns its place; the API-endpoint line ('Mirrors GET /api/...') is the least load-bearing element but is minor overhead.

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 carries the return-value burden and does so: it names the status fields, explains the projection methodology, and disambiguates the two currency fields. Nothing an agent needs to interpret the response correctly appears to be missing.

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 per the rubric the baseline is 4. There is no parameter surface to add semantics to, and the description correctly spends its words on return-value semantics instead.

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+resource ('List this account's spend budgets') and enumerates the status fields returned (spend, projected total, ok/warning/exceeded, forecast). It explicitly distinguishes itself from the cost tools, which lack the budget currency semantics, so an agent can tell it apart from siblings 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?

It contrasts budget currency with 'the USD base the cost tools return,' which gives implicit context on when this tool is the right one. However, there is no explicit when-to-use, prerequisites, or named alternative routing (e.g., vs. query_costs or list_anomalies), so usage is implied rather than stated.

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