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

Annotations already establish read-only, idempotent, non-destructive behavior; the description adds the meaningful access prerequisite ('Scale plan or higher') not present in annotations or schema. It does not describe error cases or return format, but output schema exists and safety profile is covered, so the added context 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?

Two short sentences with no filler; the core behavior is front-loaded and the plan requirement is a distinct, necessary detail. Every clause 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 one-parameter read-only getter, the combination of description, full schema, output schema, and annotations covers what an agent needs: what to pass, where the id comes from, the access requirement, and safety. No significant gap remains.

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 sole parameter id is fully documented in the schema (100% coverage), including where the value comes from (list_themes/create_theme). The description itself adds no parameter detail beyond the schema, so 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?

States a specific verb ('Fetches'), resource ('theme'), and selection criterion ('by id'), which separates it from list_themes (all themes) and mutation tools like create_theme/update_theme. The title is generic, but the description disambiguates it.

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 a clear usage context: retrieve a single theme when an id is available, and only on Scale plan or higher. It does not explicitly name alternatives like list_themes or update_theme, but the singular 'by id' and plan constraint make selection straightforward.

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