list_contacts

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

With no annotations provided, the description must disclose behavioral traits. It states 'List all contacts' and 'paginated browsing,' which implies a read-only operation with pagination. However, it does not explicitly mention that it has no side effects, nor does it describe the return format or any rate limits. Since 'list' is inherently non-destructive, it gains some credit, but the description could be more transparent about behavior beyond what is obvious from the name.

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 two short sentences, front-loaded with the purpose, followed by a clear alternative and use case. No filler or redundancy. Every sentence earns its place, making it appropriately sized and well-structured.

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?

The tool has 4 optional parameters and no output schema or annotations. The description covers the main purpose, alternative, and use case, but does not mention return value or pagination specifics (beyond 'paginated browsing'), which are common expectations. Still, for a simple list tool with well-described parameters, the description is reasonably complete. A small gap is the lack of any note about ordering or default behavior.

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 parameters (limit, offset, status, folder_id). The description merely says 'optional filters' without adding any meaning beyond what the schema already provides. This matches the baseline of 3, as the schema does the heavy lifting and the description adds no extra parameter semantics.

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 clearly states the tool's function: 'List all contacts in your CRM with optional filters.' It specifies the resource (contacts) and the action (list), and distinguishes itself from the sibling tool search_contacts by noting that search_contacts is for keyword search. This is a specific verb+resource with clear scope.

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 explicit usage guidance by naming an alternative: 'Use search_contacts for keyword search.' It also states the intended use case: 'This is for paginated browsing,' which tells the agent when this tool is appropriate. This is an explicit when/alternative distinction, matching the highest level.

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