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

Annotations already establish readOnly, idempotent, and non-destructive behavior. The description adds useful context beyond that: entries are 'projected from CapabilityContract and Merchant records,' are 'neutral,' and carry 'No commercial obligation. Risk R0; PUBLIC.' This enriches the behavioral profile without contradicting the 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 concise and front-loaded: the core action and resource appear first, followed by scope and risk in short, information-dense clauses. Every sentence earns its place, and there is no filler or repetition of the tool name/title.

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 high parameter count (15), no output schema, and zero parameter documentation, the description is not complete enough for correct invocation. It does not explain result shape, pagination, ranking-policy specifics, filter combination behavior, or how canonical/neutral entries are determined, leaving significant gaps for an agent.

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 0%, and the description only mentions 'explicit filters and ranking policy' without mapping any of the 15 parameters to specific behavior or explaining their semantics. Parameter names and enums are suggestive, but the description does not compensate for the complete absence of schema-level documentation.

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 action ('List'), a resource ('canonical Axiom Directory'), and a distinctive scope ('neutral directory entries projected from CapabilityContract and Merchant records'). This differentiates it from sibling get_directory_entry, which appears to fetch a single entry, and from compareServices or find_paid_service, which imply comparison or paid discovery.

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 explicit when-to-use guidance or comparison with alternatives. It implies a search/filter use case via 'explicit filters and ranking policy,' but it never states when to prefer search_directory over siblings like get_directory_entry, compareServices, or find_paid_service.

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