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

Annotations already flag destructiveHint=true and openWorldHint=true, and the description adds real value on top by disclosing a specific destructive side effect: 'Passing post_category replaces all of the post's categories.' It also notes the underscore-key refusal rule for meta_input. It stops short of covering reversibility, revisions, or error behavior.

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 tight sentences, front-loaded with the verb and resource, with the destructive caveat placed last where it is still salient. The field list slightly duplicates the schema but serves as a quick capability summary.

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 nested objects and no output schema, the description covers partial-update semantics, custom-field restrictions, and scheduling behavior adequately. It is thin only on return shape and what happens to unspecified fields, which the schema only implies.

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?

With 75% schema coverage the schema does most of the work, but the description adds meaning beyond it: partial-update semantics (only pass the fields to change), the fields/meta_input split, and the category-replacement consequence. It also mentions 'slug, date' which are not enumerated in the fields schema, helping the agent use additionalProperties.

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 post by ID') plus the set of updatable fields, so the agent knows exactly what is being modified. It does not differentiate from plausible siblings such as wp_alter_post or wp_write_blocks, which an agent could easily confuse with this one.

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 explains mechanics ('Pass the fields to change in fields'), which implies usage for partial updates, but it never states when to choose this over wp_alter_post, wp_create_post, or wp_write_blocks, nor any exclusions.

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