List cards

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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true. The description adds valuable behavioral context: pagination support (before/after) and the efficient counting trick. There is no contradiction, and the description enhances understanding beyond annotations.

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 two sentences plus a bolded tip. Every sentence serves a purpose: stating the main function, providing a counting pattern, and listing filters. No fluff, front-loaded with key information.

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 list tool with 6 parameters and no output schema, the description covers the core use cases (listing, filtering, counting). Lacks details on return format or error conditions, but annotations (readOnly, idempotent) reduce the need. Adequate for typical agent use.

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 100% coverage with descriptions for all parameters. The description reinforces key usage (total_count trick, date filter) but does not add new semantic meaning beyond what the schema already provides. Baseline of 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 clearly states 'List card inventory on your account' which is a specific verb-resource pair. It also highlights filtering by date_created and metadata, but does not explicitly differentiate from sibling list tools like 'lob_letters_list' or 'lob_cards_get', though the context of cards is clear.

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 provides explicit advice for efficient counting: pass 'include: ['total_count']' with 'limit: 1'. It also mentions filtering options. However, it does not explicitly state when not to use this tool or list alternatives, but the tips are actionable and contextually relevant.

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