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

Annotations already flag destructive/non-idempotent, but the description adds substantially more: it replaces core files site-wide, records no undo point, runs no test requests (unlike wp_update_plugin), and returns updated=false with a message when already current. These are exactly the facts an agent needs before an irreversible mutation.

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?

Scope and the exclusion of plugins/themes are front-loaded, and every clause carries information. It is dense and runs several ideas together with semicolons, which costs a point on readability but nothing is wasted.

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 parameters and no output schema, the description has to carry purpose, preconditions, failure modes, return shape, and blast radius – and it does all of these. Nothing material is left for the agent to infer before an irreversible core upgrade.

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?

There are zero parameters, so the baseline is 4. The description usefully compensates for the absent output schema by explaining the return contract (updated true + new_version, updated false + message, or the updater's error) and by noting it applies only to the single site the connection reaches.

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 WordPress core itself') and immediately excludes plugins and themes, which is exactly the ambiguity among the wp_update_plugin / wp_update_theme siblings. It also specifies that WordPress's own core updater is used rather than a custom path.

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?

Explicitly routes the agent through wp_get_update_status to see available offers before calling, and names a hard precondition (needs update_core) plus a blocking condition (refused when DISALLOW_FILE_MODS is set). An agent knows both when to call it and when it will fail.

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