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

Adds substantial behavior beyond readOnlyHint=true: the URL is tokenized and works without an authenticated wp-admin session, private and password-protected records are never exposed, and a block rendered with contentId runs as if placed on that record so fabrement_get_field() and get_queried_object_id() resolve. That is exactly the context an agent needs and it is consistent with the read-only annotation.

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?

Front-loaded with what the tool produces, then target-by-target routing, then constraints and prerequisites — a sensible order with no filler. The prose is dense and runs long with em-dash clauses, which costs a little scannability.

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 5-parameter preview tool with an output schema (so return shape needn't be documented), the description covers every mode, the privacy constraint, and the required first-call documentation. Nothing an agent needs to call it correctly is missing.

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% and the property descriptions already explain id, target, context, postType and contentId, including the omitted-postType default. The description's target paragraphs largely restate that mapping, adding only light framing ('drafts included', 'optionally rendered ON a record'). Baseline 3 for a fully documented schema.

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 concrete verb and artifact: returns a tokenized URL that renders a build in the browser without a wp-admin session. It then enumerates the three preview modes (content, template, block) so an agent can tell exactly which resource shape it is producing, well beyond the tautological title 'Preview'.

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?

Declares the tool MANDATORY after every save and routes the agent per target: content for a record through its template, template for the assembled layout, block for an isolated block. It also sets a prerequisite ('get-skill-doc {id:"preview-contract"} — read it before the first call'). No explicit when-not-to-use or sibling alternative is named, which keeps it just short of a 5.

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