Get Service Cost Breakdown

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 reveals what the output contains (service-level breakdown, usage, SKU info) but says nothing about read-only status, required Billing permissions, aggregation behavior across projects, pagination, or response format. For an analysis tool with zero annotation coverage, this 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 a single front-loaded sentence with no filler; the core purpose appears immediately. It is appropriately concise, though it lacks any secondary structure such as usage notes or sibling differentiation, which would strengthen it given the dense sibling context.

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 and no annotations, the description must carry more weight, but it leaves key questions unanswered: what the return structure looks like, how this tool differs from gcp-billing-analyse-costs, and what the projectId filter changes about the breakdown. An agent navigating ten billing siblings cannot confidently select this tool based on the provided text alone.

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 100%, so the schema fully documents all three parameters including the required billingAccountName format and the timeRange enum values. The description adds nothing about parameters beyond the schema, but per the baseline for high schema coverage, a 3 is appropriate.

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 states a specific verb and resource: 'Get detailed cost breakdown by Google Cloud service with usage and SKU information.' This clearly distinguishes it from sibling list/account tools like gcp-billing-list-accounts and gcp-billing-list-skus. However, it does not differentiate itself from the closely related sibling gcp-billing-analyse-costs, which likely overlaps in purpose.

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, no exclusion criteria, and no reference to sibling tools. With 10 billing-related siblings including gcp-billing-analyse-costs, gcp-billing-detect-anomalies, and gcp-billing-cost-recommendations, an agent has no evidence to decide which billing analysis tool fits the task.

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