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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint. The description adds valuable non-schema behavior: it enumerates the return fields (key, name, template kind, native size, categories, look description, preview URL), notes that no API key is needed, and suggests the next logical call. This is rich context beyond the structured 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?

Four concise sentences, each earning its place: the first defines the resource and output fields, the second gives usage context, the third specifies the next step, and the fourth clarifies authentication. Information is front-loaded 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?

For a simple read-only list tool with no output schema, the description is fully complete: it covers what the tool returns, when to use it, how to proceed with a chosen key, and auth requirements. The annotations cover safety and idempotency, and the schema covers the optional filters. Nothing an agent needs to call it correctly is missing.

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%, with detailed descriptions and enums for kind and category. The tool description does not add parameter-level detail beyond the schema, but it does not need to; baseline 3 is appropriate when the schema already carries the burden.

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?

States a specific verb ('Browse') and resource ('ready-made designs (presets) a card can start from'), and lists the exact fields returned. It distinguishes itself from list_templates by framing presets as ready-made designs used when there is no saved template, so an agent can tell them apart.

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?

Gives explicit when-to-use guidance: 'Start here when the user wants a social card and has no saved template.' It also names the follow-up action (preview_card). However, it does not explicitly name the alternative tool or state when not to use it beyond that conditional, so it stops short of a perfect 5.

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