List services

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

With no annotations, the description carries the behavioral disclosure burden. It explicitly states the auth requirement ('No API key required') and the filtering behavior ('all active'), and the 'List' verb implies a read-only operation. It does not mention rate limits or response format, but these are not material for this simple list.

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 only three short sentences, with the core purpose and data contents front-loaded. Every sentence adds useful information and there is no redundancy or filler.

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 that this is a zero-parameter, read-only listing tool with no output schema, the description is complete: it states the resource, scope, data included, auth requirement, and intended use. An agent has enough information to select and invoke it correctly.

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 tool takes zero parameters, so the input schema already fully covers invocation. The description adds no parameter details, but none are needed; the baseline of 4 for a parameterless tool applies.

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 action ('List') and resource ('all active SMS verification services') and summarizes what is included ('stock and minimum-price summaries'). It does not explicitly differentiate from sibling tools like get_service, but the 'all active' qualifier helps set 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 gives a direct use case: 'Use this to discover available services and their slugs/codes.' It also notes that no API key is required. It stops short of saying when to prefer alternatives, but the usage context is clear enough for a zero-parameter listing tool.

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