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

Goes well beyond the destructive/openWorld/non-idempotent annotations: discloses kses filtering/script stripping, the full refusal-code list, field_dropped restore behavior, the 1 MB undo limit with undo_available false, and the Royally human-approval gate that defers all site changes. This is exactly the extra behavioral context annotations can't carry.

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?

Front-loads the operation and scope, then layers prerequisites, dry_run, and refusal codes efficiently. Dense but nearly every clause earns its place; the parenthetical site tag and approval note add slight bulk but are informative.

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 still characterizes return behavior (dry_run preview fields, refusal codes, undo_available/undo_reason) and the approval-queue side effect, leaving nothing essential for a correct invocation unstated.

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 80% and the schema documents dry_run, site_id, theme_slug, and expected_sha256. The description adds real semantic meaning for dry_run (returns allowed/reason/sha256/byte counts, changes nothing) and expected_sha256 (refuses with expected_mismatch on drift), beyond the terse schema text; only css is left undocumented but is self-evident.

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 and resource ('Update the active theme's custom CSS') and adds the crucial scope note that it replaces the whole stylesheet, distinguishing it from the read sibling wp_get_custom_css. An agent can tell exactly what this does.

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?

Explains prerequisites (admin toggle, unfiltered_html capability), the dry_run preview path, and the expected_sha256 concurrency guard ('sha256 of the CSS you read'), implying a read-first workflow. It doesn't explicitly name wp_get_custom_css as the read alternative, so not a full 5.

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