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

Goes well past the annotations: it discloses the preview/confirm handshake, that the previous value is backed up, that the site cache is cleared afterward, and the prerequisites (Bridge 1.7.0+, administrator application password). Those are exactly the side effects and setup requirements an agent needs before calling a destructive write.

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?

Four short sentences, each carrying distinct information: scope, negative boundary, workflow, prerequisites. The scope constraint is front-loaded and nothing is repeated from the annotations.

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 critical unknowns: reversibility (backup), caching, auth, and the confirm gate. Minor gaps remain on what 'site' refers to and what happens if the key does not exist, but an agent has enough to call it safely.

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 50% (key and confirm documented, site and value not), so the description has to compensate. It does partially: it clarifies that value must be a plain value (empty string example for a switch) and constrains key to an existing _crb_* option sourced from wp_theme_options_get. The 'site' parameter is left entirely undefined.

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 ("Set one existing theme option") plus a scope limit ("holds a plain value") and an explicit negative boundary ("never creates options or overwrites a structure"). That boundary is what separates it from the Carbon Fields row tools and from wp_theme_options_get without needing the schemas.

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 concrete use case (turning the promo bar off) and a clear operating procedure: preview by default, set confirm only after agreement. The when-not case is implied by "never creates options or overwrites a structure", but the sibling it points at for the read side (wp_theme_options_get) only appears in the schema, not the description.

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