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

Annotations already declare readOnlyHint=false, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds the PATCH-like partial-update behavior (omitted fields are preserved), which is genuine context not in the annotations, but says nothing about permissions, publish side effects, or validation failures.

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 sentences, front-loaded with the action and followed by the key operating instruction, with no filler. It is tight, though the second sentence restates fairly standard partial-update semantics rather than adding new information.

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 10-parameter write tool with no output schema, the fully documented input schema and safety annotations carry most of the load. The description still leaves the agent without routing guidance against the ACF/sibling update tools, which is a real gap for this crowded namespace.

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 every parameter including the status enum and featured_media is documented in the schema itself. The description adds no parameter-level semantics beyond that, 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 and resource ('Update an existing WordPress post'), which clearly separates it from wp_update_page or wp_update_custom_post. However, it never names a sibling or scopes itself explicitly, so the differentiation is left to the agent's inference.

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?

'Only provide the fields you want to change' gives useful partial-update guidance but no when-to-use or when-not-to-use framing. Nothing tells the agent when to prefer acf_update_post_fields or acf_update_post_fields for custom fields, so usage is only implied.

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