billy_list_contacts

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

With no annotations provided, the description carries the full burden. It discloses the core behavior (listing) and adds that filtering and pagination are optional, which is helpful. However, it does not mention return format, default pagination behavior, sort defaults, or any side effects (though 'list' implies read-only). It adds some value beyond the name but remains minimal.

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 sentence, front-loaded with the action and resource, and contains zero wasted words. It efficiently communicates the core functionality without unnecessary elaboration.

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 there is no output schema and no annotations, the description is short but covers the essential behavior. It does not describe return values, edge cases, or what happens with no filters, but for a simple list tool it is minimally viable. More detail about response shape or default behavior would improve completeness.

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 has 100% coverage, with descriptions for all six parameters. The description only recaps 'optional filtering and pagination' without adding new syntax or format details. Baseline of 3 is appropriate as the schema does the heavy lifting and the description adds no extra parameter-specific 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 states 'List contacts' with a specific verb and resource, clearly distinguishing it from 'billy_get_contact' (single contact retrieval). The addition of 'optional filtering and pagination' further scopes the behavior and differentiates it from other list tools like 'billy_list_invoices'.

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 implies usage through the tool name and the verb 'List', but it does not explicitly state when to choose this over 'billy_get_contact' or mention any exclusions. It provides clear context that it lists contacts with optional filtering/pagination, but lacks explicit alternatives or when-not guidance.

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