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

Annotations already mark the operation read-only and idempotent; the description adds valuable behavioral detail: licensing requirements, the need to call again with a license key, and that a ready-to-fetch URL is returned. It does not cover failure modes, but the core behavior is well disclosed.

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?

Two sentences with no filler. The core purpose is front-loaded, and the conditional licensing details are packed efficiently into the second sentence.

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 one required parameter, the description covers the workflow, authentication nuance, and expected result. Annotations cover the safety profile, and no output schema is needed because the return value is described as a URL.

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 coverage is 100%, so the baseline is 3. The description adds workflow meaning beyond the schema by explaining that paid themes require buying a license and calling again with license_key, and that the result is a ready-to-fetch URL. This is modest but genuine added context.

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 opens with a specific verb and resource: 'Get a theme's zip download URL.' It is clearly distinguished from siblings like get_theme or get_component, which fetch metadata or components rather than a download URL.

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 usage conditions: free themes need no credentials, paid themes require an active license, and the caller should re-invoke with license_key after purchasing. It does not explicitly contrast with sibling tools, but the resource difference makes the intended use clear.

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