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

Annotations already declare this is a non-read-only, non-destructive, idempotent update. The description adds useful behavior beyond annotations: config and style are merged shallowly, and the home page slug has a special restriction. It does not discuss permissions or error behavior, but the key mutation semantics are 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?

The description is front-loaded with the core action and updatable fields, then adds the merge behavior and slug constraint without repetition. Every sentence carries useful information for invoking the tool correctly.

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?

Given the annotations, 100% schema coverage, nested config object, and output schema, the description is largely complete. It explains the mutation semantics and one important edge case, though it could do more to route between this tool and closely related site-update siblings.

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 adds meaning beyond the schema by explaining shallow merge behavior for config and style and by stating the home page slug constraint, which the slug schema field does not mention.

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 states a specific verb and resource: update a registration site page, with the updatable fields named as title, slug, config, and style. It is clearly distinct from create/delete/duplicate/read siblings by resource, but it does not explicitly distinguish itself from update_site_settings or update_site_block.

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 implies use when modifying an existing page and gives one concrete exclusion: the home page's slug cannot be changed away from '/'. However, it does not say when to choose this tool over update_site_settings, update_site_block, or update_site_section_styles, nor does it state prerequisites beyond the schema.

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