get_cost_by_compartment

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states the tool retrieves cost data but doesn't mention whether this is a read-only operation, requires specific permissions, has rate limits, or involves data freshness considerations. For a tool that likely accesses billing/financial data, this lack of behavioral context is a significant gap.

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 well-structured and appropriately sized. It begins with a clear purpose statement, followed by organized sections for 'Args' and 'Returns'. Each sentence serves a specific function without redundancy. Minor improvements could include more explicit formatting, but overall it's efficient and front-loaded.

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?

Given the tool's moderate complexity (3 parameters, no output schema, no annotations), the description is partially complete. It adequately covers parameters and return format but lacks behavioral context and usage guidance. Without annotations or output schema, the description should ideally mention more about authentication needs, error conditions, or data limitations to be fully comprehensive.

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 description adds substantial value beyond the input schema, which has 0% description coverage. It clearly explains each parameter's purpose: 'tenant_id: OCID of the tenancy', 'time_usage_started: Start time in ISO format (YYYY-MM-DD)', and 'time_usage_ended: End time in ISO format (YYYY-MM-DD)'. This provides essential semantic context that the schema alone lacks, though it could benefit from mentioning format constraints or examples.

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 tool's purpose: 'Get cost breakdown by compartment for a tenancy.' It specifies the verb ('Get'), resource ('cost breakdown'), and scope ('by compartment for a tenancy'), making it easy to understand what the tool does. However, it doesn't explicitly differentiate from its sibling 'get_cost_by_service' or other cost-related tools, which prevents a perfect score.

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 provides no guidance on when to use this tool versus alternatives. It doesn't mention sibling tools like 'get_cost_by_service' or 'get_cost_usage_summary', nor does it specify prerequisites, exclusions, or appropriate contexts for usage. This leaves the agent without clear direction on tool selection.

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