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

With no annotations, the description carries the full burden. It discloses the auth requirement, the read operation nature, and provides an expected return structure with sample values. This is more transparent than typical, though it does not mention anything about side effects or pagination (likely irrelevant for a simple list).

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 three concise lines: the action, the requirement, and the return format. Each sentence earns its place with no redundancy or filler.

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 simple list tool with no output schema, the inline return example provides necessary context about what the tool returns. The description doesn't explain default filtering behavior, but that is covered by the schema. Overall, it is complete enough for this level of complexity.

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 parameter meaning. It does not mention the include_terminated parameter at all. The one optional parameter's meaning is left entirely to the schema's title and default, which is minimal but not negligible. Still, the description adds no value here.

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 'List your on-demand compute instances with month-to-date spend,' which clearly specifies the verb, resource, and a distinctive detail (spend). This differentiates it from sibling tools like get_compute_instance or list_compute_volumes.

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 states a clear prerequisite ('Requires: API key with read scope'), giving the user essential context for when this tool can be used. It does not explicitly contrast with alternatives, but the scope is reasonably clear from the name and description.

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