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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds valuable behavioral context beyond annotations: idempotent and cacheable per slug, returns a 404-shaped error_payload on unknown slug, and requires exact slug matching with no normalization. This provides actionable knowledge about edge cases without contradicting 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 structured with clear sections (purpose, WHEN TO CALL, WHEN NOT TO CALL, behavior notes) that make it scannable. Every sentence contributes new information; the length is justified by the decision logic and edge-case guidance, and the core purpose is 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?

With a single parameter, a rich output schema, and comprehensive annotations, the description fully covers all contextual needs: what the tool returns, when to use it, when not to use it, error handling, caching, and parameter matching rules. No gaps remain for this tool's 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 100% for the single slug parameter, but the description adds extra meaning by explaining the origin of slugs (from clusters.list/principles.list), the requirement for exact matching with no normalization, and the error behavior on unknown slugs. This goes beyond the schema's basic type and 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 opens with 'Get one principle cluster by stable slug', which is a specific verb+resource+scope statement. It clearly distinguishes from siblings by explicitly naming alternatives (clusters.list, principles.get, principles.search) and by stating the return contents (cluster definition, shared rationale, member principle slugs + titles).

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?

Provides explicit WHEN TO CALL and WHEN NOT TO CALL sections with named alternative tools for each exclusion case. It also gives a performance guideline advising not to loop principles.get over members because the response already embeds member slugs/titles, which goes beyond typical tool descriptions.

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