preflight_htmlValidate static HTML and inline explicit image/font/CSS assets without publishing. Returns ready, issues and prepared HTML. Does not visually render or fetch external URLs.
| Name | Required | Description | Default |
|---|---|---|---|
| id | No | Existing page to check for accidental content removal. | |
| html | Yes | ||
| assets | No |
Changes observed during successful MCP inspections.
Input schema / properties / idAdded value: +{
+ "description": "Existing page to check for accidental content removal.",
+ "type": "string"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly/idempotent/non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavioral context: no visual rendering, no external URL fetching, and that it returns ready, issues and prepared HTML. It could still say more about what 'issues' look like or whether failures block publishing.
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 scope, followed by return values and exclusions. No filler or redundancy.
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?
Return values are named so no output schema is needed, and the annotations cover the mutation/safety dimension. Missing pieces are minor: no guidance on asset limits (maxItems 64), and the id-vs-html interaction used for accidental content removal is unexplained.
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 coverage is only 33%, so the description must carry weight — it partially does by clarifying that assets are 'inline explicit' image/font/CSS, mapping to the assets array. However, the required html parameter and its relationship to the optional id are never explained, so gaps remain for a 3-param tool.
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 (validate) and resource (static HTML plus inline image/font/CSS assets), and the phrase 'without publishing' cleanly distinguishes it from the sibling publish_html. An agent can identify the job without opening the schema.
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?
'Without publishing' implies the pre-publish validation workflow against publish_html, and 'Does not visually render or fetch external URLs' supplies explicit exclusions that tell the agent when this tool is the wrong choice. It stops short of naming publish_html as the follow-up, so it is not a full when/when-not statement.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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