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

Annotations cover the safety profile, but the description adds important operational prerequisites and the required ACF field naming convention. It does not explain overwrite/merge behavior, but it meaningfully extends the structured metadata.

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 purpose, then fields format, then naming constraints, then prerequisites. Every sentence adds actionable information with no filler.

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 mutation tool with rich annotations and full schema coverage, the description supplies prerequisites and field-format guidance. It omits whether unspecified ACF fields are left untouched or how existing values are handled, but it is otherwise complete enough to call correctly.

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 is 3. The description adds useful meaning by requiring ACF field NAME format (lowercase_with_underscores) and giving a concrete JSON example, which clarifies how the fields parameter must be formed.

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: set ACF values on a page/post. It also explains the intended outcome, populating ACF-driven templates, making it clearly distinguishable from getter siblings like wp_get_acf.

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 gives clear context and prerequisites: writes enabled, plugin transport, ACF active, and Xyle Connector v0.2.3+. It does not explicitly name when to use this over alternatives like wp_update_page or wp_patch_page, so it falls short of full routing guidance.

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