cost_breakdown

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

Annotations already declare readOnlyHint=true and destructiveHint=false. Description adds behavioral details: returns top-N items ranked by cost descending, default months=1 includes current month. This goes beyond annotations with specific operational behavior.

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 sentences, minimal and efficient. First sentence states purpose with examples, second provides alternative. No redundant information.

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?

No output schema, but description notes returns top-N ranked list. Lacks details on cost format (e.g., currency), but sufficient for typical use. Annotations and schema fill gaps well, making it nearly complete.

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 coverage is 100% with descriptions for all parameters. Description does not add significant new meaning; it restates the grouping dimension and cloud alias, which are already in schema. Baseline 3 is appropriate as schema fully documents parameters.

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?

Description states 'simple cost breakdown by service, project, or cloud provider' with examples, clearly indicating the tool's function and output (top-N ranked by cost descending). This distinguishes it from siblings like run_query for complex queries.

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?

Explicitly says 'Use this when the user wants a simple cost breakdown' and provides an exclusion: 'For complex multi-filter or multi-metric queries, use run_query instead.' This gives clear when-to-use and when-not-to-use with an alternative tool.

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