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

The annotations already establish a read-only, non-destructive, closed-world operation. The description adds that the result is a short guide and clarifies that it explains purchasing rather than performing a purchase, but offers little further behavioral context such as whether the guide is static or personalized.

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?

One front-loaded sentence states the action, audience, and three components of the guide without filler. Its length is well matched to a simple parameterless onboarding tool.

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?

For a zero-parameter, read-only guide with an output schema, the description provides the audience, purpose, and content scope needed to select and invoke it correctly. Return-shape details can be handled by the output schema, and this simple operation does not require extensive prerequisites or caveats.

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 has no parameters, so there is no argument syntax or semantics requiring clarification. The empty schema and description consistently support a straightforward zero-argument invocation.

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 pairs a specific verb and resource—“Get a short getting-started guide”—with the Letter IRL product and a new-user audience. Listing app capabilities, prepaid-letter purchasing, and example prompts also distinguishes it from operational siblings such as list_letter_packs and request_send.

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?

“For new Letter IRL users” establishes a clear onboarding context, while “example prompts to try next” positions the tool as an entry point rather than a transaction tool. It does not explicitly state when not to use it or name an alternative for experienced users or specific tasks.

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