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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the agent knows this is a non-destructive mutation. The description adds important behavioral context beyond annotations: exceeding the account's slot count returns 403 `site_limit_reached`, and the template_id merge behavior is shallow per top-level key. These are meaningful operational details not in the 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 repeats itself: 'Only `url` is required; every other field defaults to a new-site configuration' appears twice, and 'Fields for creating a site' duplicates the title. The template merge behavior is front-loaded well, but the duplication wastes space and muddies structure.

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 16-parameter creation tool with full schema coverage and annotations, the description covers the critical behavioral aspects: required field, default behavior, error on slot limit, and template merge semantics. No output schema exists, but the description doesn't need to explain returns for a creation endpoint. It's nearly complete, missing only explicit guidance on template vs manual configuration.

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% and covers all 16 parameters with rich nested descriptions, so the schema does the heavy lifting. The description adds the template_id override semantics (shallow, per top-level key) which is valuable beyond the schema, but only marginally. Baseline 3 is appropriate given full schema coverage.

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+resource ('Create a site') and clearly distinguishes from siblings like update_site and create_site_template. The duplication of the schema title ('Fields for creating a site') is wasteful but the core purpose is unambiguous.

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 says only `url` is required and others default to new-site configuration, which is useful context, but there is no explicit when-to-use or when-not-to-use guidance. It doesn't mention create_site_template as an alternative for reusing a template, nor when to prefer template_id versus individual fields.

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