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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered; the description adds real value beyond them with 'Nothing is prepared or charged', which tells the agent this is a pure information step distinct from prepare_card/send_card. The disclosed return contents (including the upload link and Christmas order dates) further describe what the agent will get back. It stops short of describing pagination or error conditions, but for a static-options lookup that is a minor gap.

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 trigger condition is front-loaded, the payload list is compact, and the workflow instruction comes last where an agent will act on it. The enumeration of card occasions and payload fields is slightly dense but each item is decision-relevant, and there is no 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?

With an output schema present, the return-value recap is technically redundant, but here it doubles as guidance on what the agent can hand back to the user, and the 'call it first / then create_card_picture' ordering covers the multi-tool flow. Combined with the no-charge assurance, an agent has enough to invoke this correctly without consulting siblings.

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 both parameters are enums with self-explanatory schema text (language, upload_purpose with 'reference' vs 'print'). The description only alludes to the upload link and picture brief, adding no syntax or defaulting detail beyond what the schema already states, so the baseline 3 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 names a concrete verb+resource ('get card options' for mailing a greeting card by post) and enumerates the returned payload: card format, picture brief, text-front option, message limit, price, Christmas order dates and upload link. It also scopes the offering (Christmas, birthday, wedding, anniversary, baby, thank-you, condolence cards to people in the United States), which separates it from the letter-related siblings.

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?

It gives explicit entry conditions ('Use this when the user wants to mail a greeting card by post') and hard sequencing ('Call it first. Then call create_card_picture'), which routes the agent through the correct multi-step flow. What is missing is an explicit exclusion, e.g. that letters use list_letter_types or that non-US recipients are out of scope, so the when-not case must be inferred from the scope sentence.

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