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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=true, so safety is covered. The description adds useful return-shape context (name => value pairs, repeaters, groups, relationships) that annotations do not provide, but says nothing about value formatting (raw vs. formatted) or permission requirements.

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?

Two tight sentences with zero waste: the action and scope are front-loaded, then the return shape adds value. Every clause earns its place.

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 usefully characterizes the returned data (field name => value pairs, including repeaters/groups/relationships), and annotations cover the safety profile. Minor gaps remain around value formatting and multi-site behavior, but it is largely complete for a read tool.

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 description coverage is 100%, so both post_id and site_id are already documented in the schema. The description only restates the post/page targeting for post_id without adding syntax, format, or fallback behavior beyond the schema, making the baseline 3 appropriate.

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 ('Get') and resource ('ACF custom field values for a specific post/page'), and the scoping to a single post reasonably distinguishes it from acf_get_field_group (group config) and acf_get_options (options pages) by implication. The sibling differentiation is implicit rather than named, so it falls short of a 5.

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 when-to-use, prerequisites, or alternatives are stated. The agent is not told when to prefer this over acf_get_field_group or acf_get_options, nor what 'ACF' context prerequisites exist. Usage is only faintly implied by 'for a specific post/page'.

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