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

Annotations already flag destructive/openWorld/non-idempotent, and the description adds context the annotations cannot: changes are queued for human approval in Royally and nothing on the site changes until a person approves. It also discloses the two hard gating conditions (admin toggle, allowlist) that determine whether the call succeeds.

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-loaded with the action, then prerequisites, then the approval behavior. The parenthetical site string is boilerplate duplication of site_id but the rest is dense with no wasted clauses.

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 destructive mutation with no output schema, it covers the safety model (approval gate), access gating (toggle + allowlist) and target site. The remaining gap is what a successful enqueue returns and how to enumerate permissible mod names.

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 67%; value and the single-enum site_id are already documented. The description adds real semantics for the otherwise undocumented mod_name (it must pass an allowlist, extendable via filter), but gives no hint on discovering valid mod names or the expected shape per mod, so it only partially compensates.

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 a single theme customizer setting") and scopes it to one mod, which cleanly separates it from the read-side sibling wp_get_theme_mods. An agent knows exactly what is being mutated.

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?

Explicitly lists the preconditions for use: the "Allow AI to modify theme appearance" admin toggle must be on and the mod name must be on the allowlist, with the royal_mcp_writable_theme_mods filter named as the extension path. It does not name a sibling alternative for reading current values (wp_get_theme_mods), so it stops short of full when-to-use-vs-alternative routing.

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