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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety behavior is covered. The description adds useful status-state context (awaiting payment, paid, shipped, failed), but it does not describe freshness, auth needs, or response shape.

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?

It is a single front-loaded sentence with no wasted words, and the enumerated status states directly serve the purpose of the 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 simple read-only getter with one fully documented parameter and no output schema, the description supplies the key conceptual return categories. A minor gap remains around exact response shape or whether the status labels are literal strings.

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?

Schema description coverage is 100%, and the single letter_id parameter is already documented in the schema as coming from send_letter. The description adds no further parameter semantics, so the baseline 3 is appropriate.

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 a clear verb and resource: it shows whether a letter order is awaiting payment, paid, shipped, or failed. This is specific and distinguishable in practice, though it does not explicitly contrast itself with siblings such as get_letter_price or send_letter.

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?

Usage is implied: an agent would call this to check a letter's lifecycle status, likely after send_letter. However, there is no explicit when-to-use guidance, no exclusions, and no named alternative for price or sending.

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