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

Annotations already declare readOnlyHint and idempotentHint, and the description adds 'No API key needed' — a useful authentication trait not covered by annotations. It also describes the response fields, which is additional behavioral context. It does not discuss pagination or rate limits, but for a read-only listing tool with strong annotation coverage, this is sufficient.

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?

Three sentences with no fluff: the first lists what is returned, the second tells when to use it and gives the next step, and the third states authentication. Key information is front-loaded, and 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?

For a simple read-only tool with no required parameters and no output schema, the description covers the essential context: what the tool returns, when to invoke it, the follow-up action, and auth requirements. It does not mention result ordering or pagination, but those are minor gaps for a preset-listing tool, so completeness is high but not perfect.

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%, so the baseline is 3. The description does not add parameter-level detail beyond the schema; it mentions return fields like 'one-line look description' which relates to query, but it does not elaborate on how to combine filters or value formats. The schema already carries the semantic weight, so a 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 the tool lists ready-made starter designs and enumerates the exact fields returned (key, name, template kind, native size, categories, look description, preview URL). It distinguishes itself from saved-template workflows by using 'presets' and 'no saved template', and it names preview_card as the follow-up, helping an agent pick it apart from list_templates.

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 explicit guidance: 'Start here when the user wants a social card and has no saved template' and then directs to preview_card. It establishes a clear context and next step, but it does not explicitly name the alternative (e.g., list_templates) for cases where a saved template exists, so it falls short of a full when/when-not/alternatives statement.

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