wp_update_acf_fields

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

No annotations are provided, so the description carries the full behavioral disclosure burden. It does disclose one genuine behavioral trait — '(creates snapshot before update)' — which implies rollback capability and signals the update is material. However, it omits other important behaviors for a mutation tool: whether the update merges with or replaces existing ACF values, how nested/repeater fields are handled, and whether validation failures are surfaced. One useful disclosure among several needed merits a 3.

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 a single sentence with the primary action front-loaded and the secondary behavioral note (snapshot) efficiently appended in parentheses. Zero wasted words; the structure prioritizes the most decision-relevant information first.

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?

This tool is genuinely complex: it accepts a nested arbitrary object (fields with additionalProperties: {}), is a mutation, and has no output schema. The description does not explain how to structure the fields object, whether partial field sets are merged or treated as a full replacement (high-risk if an agent assumes replace semantics and wipes existing ACF data), or what the tool returns. For a mutation of this complexity, the one-line description leaves too much to inference.

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% — 'fields' is described as 'ACF field key/value pairs to update' in the schema, but post_id has no schema description. The tool description adds marginal context by clarifying the target ('on a post/page'), which helps interpret post_id, but it does not explain the semantics of the fields object keys (field name vs. field key vs. field slug), which is a real ACF ambiguity. The description partially compensates for the 50% coverage gap but stops short of defining the nested object's format.

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 'Update ACF field values on a post/page' uses a specific verb and resource, clearly identifying this as the ACF-field-level mutation tool. It distinguishes itself from the 120+ siblings, notably wp_update_post/wp_update_page (standard post data), wp_get_acf_fields (read counterpart), and wp_update_settings (site settings). The parenthetical '(creates snapshot before update)' adds a distinguishing behavioral feature.

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?

No guidance is given on when to use this tool versus alternatives. With a large sibling set containing wp_get_acf_fields (read ACF values) and generic post/page updaters, the description provides no explicit routing, exclusions, or preconditions such as 'use wp_get_acf_fields first to read existing values' or 'use wp_update_post for standard post fields.' The usage context is only implied by the tool name and description.

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