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

With no annotations, the description carries the behavioral burden. It discloses that the tool lists the user's templates and describes the main fields returned (name, body, and subject). 'List' clearly implies a read-only operation, and the field-level detail adds useful behavioral context beyond the bare tool 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?

Two concise sentences with no filler. The action is front-loaded in the first sentence, and the second sentence adds both output-field information and a practical use case. Every sentence earns its place.

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 description is adequate for selecting and invoking a zero-parameter list tool, and it names some returned fields. However, it omits an identifier field in the returned templates, which an agent would likely need to subsequently get, update, or delete a template. There is also no explicit mention of output format or pagination, though the absence of an output schema raises the burden on the description.

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 zero parameters and 100% schema coverage, so there is no parameter burden for the description to carry. The description correctly implies an unfiltered listing of the user's templates, which is sufficient for a parameterless tool.

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 a specific verb and resource: 'List the user's SMS templates.' This clearly distinguishes the tool from related siblings like sms_templates_get, sms_templates_create, and email_templates_list by operation and resource type. The added statement about finding an existing template before drafting reinforces the intended purpose.

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 an explicit usage context: 'Use this to find an existing template before drafting a new one.' This helps an agent know when to call the tool, but it does not provide exclusions or compare against alternatives such as sms_templates_get or email_templates_list, so it falls just short of a 5.

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