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

Annotations already declare readOnlyHint/destructiveHint=false, so safety is covered; the description adds the meaningful precondition about needing a block theme, the exact return shape, and a note that the server marks it read-only so it executes immediately. Slight redundancy with the annotation in the 'runs straight away' sentence, but the precondition and output-shape disclosure carry real extra information.

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?

Purpose and precondition are front-loaded, but the bulk of the text is a long digression on slug-collision suffix mechanics that most callers will never need. Valuable detail, poorly rationed against the core action.

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?

With no output schema, the description supplies the full return shape ({ id, settings, styles, title } plus the variations array) and the precondition an agent needs to decide whether the call will succeed. Nothing essential to calling 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 coverage is 100%, so the baseline would be 3, but the description goes well beyond the schema by spelling out what `include_variations` actually produces: the `available_variations` shape, the `scope` values (full/color/typography), the `-color`/`-typography` suffixing rule and the `-2`/`-3` collision suffixing. The `site_id` enum is left to the schema, which is fine.

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 ('Gets the current global styles (theme.json) settings and styles') and immediately names the precondition (active block theme) and the return shape. It is clearly distinguishable from neighbours like wp_get_theme_mods, wp_get_active_theme and wp_get_site_settings.

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 applicability condition ('Requires an active block theme') and routes the agent forward by naming wp_update_global_styles `variation_slug` as the consumer of the returned slugs. It does not explicitly state when to prefer a different sibling (e.g. theme mods vs. global styles), which keeps it from a 5.

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