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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It makes clear this is a read/aggregation operation returning total spend per agent and that it can rank expensive agents. Yet it omits details such as the time period covered, whether results are sorted or limited, and any authentication or rate-limit considerations.

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?

Two short, front-loaded sentences with no filler. The first states the core result, and the second adds a practical purpose. Every sentence earns its place, even though the opening sentence closely mirrors the title.

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 aggregate tool, the description is nearly adequate: it names the output and the main use case. However, with no output schema and no annotations, it should more explicitly state the time period and ordering or limit behavior, especially given the cluster of closely related credit-usage tools.

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 and the schema is empty with 100% coverage, so the baseline of 4 applies. The description's 'in the workspace' clarifies the implicit scope of the aggregate, which is all the schema can convey.

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 clearly states the operation (get), resource (credit spend), and aggregation level (per agent in the workspace). It adds an analytic purpose ('Identifies the most expensive agents') that goes beyond the name. However, it does not explicitly distinguish itself from closely named siblings like get_credit_usage_for_agent, get_credit_usage_by_type, or get_credit_usage_monthly, so some clarity is left to inference.

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?

'Identifies the most expensive agents' implies a clear use case: cost analysis across agents. But the description never says when to choose this over the many similar credit-usage tools in the sibling list, nor does it provide exclusions or alternatives. Usage is implied but not explicitly routed.

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