cos_failure_pattern_query

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint. The description adds beyond annotations by noting the migration v25 requirement and that 'domain' is reserved for future use. No contradiction with annotations.

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 compact yet well-structured with separate paragraphs for purpose, usage, Args, and Returns. Every sentence adds value and no information is redundant.

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 presence of an output schema and three parameters, the description covers purpose, usage timing, prerequisites, parameter semantics, and return format. It leaves no important gaps for selecting or invoking the tool.

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 input schema provides zero descriptive text (0% coverage), but the description compensates with a full Args section: explains 'root_cause' filter values, 'domain' reserved status, and 'limit' range/default. This fully clarifies parameter meaning.

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 uses a specific verb ('Aggregate') and resource ('backtrack_events'), and clearly states the output (root_cause categories with examples). It distinguishes itself from sibling query tools by focusing on failure anatomy from backtrack events.

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 states 'Use before planning to avoid known failure modes' and notes the prerequisite migration v25. It does not mention when not to use the tool or alternatives, but the context is clear.

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