Convert HTML to Markdown

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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds information not in any structured field: metered charges per successful invocation, a network call to the DOMStrip service, a prompt-injection warning that returned Markdown is untrusted data, and failure modes (JavaScript, logins, bot challenges). That is exactly the kind of operational context annotations cannot express.

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 the core action and the sibling distinction in the first two sentences, then a compact Args block, then returns/cost/safety caveats. It is dense rather than long — every sentence introduces a distinct fact (cost, untrusted content, extraction limits) with no restatement of the title or schema.

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?

Despite having an output schema (so return values need not be detailed), it still anchors the return value to the sibling's output and flags that returned content is untrusted. Combined with cost, network behavior, and failure modes, an agent has everything needed to decide whether to call it and how to set mode and base_url.

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 0%, so the description carries the full burden — and does: raw_html (full document or fragment), base_url (resolves relative links to absolute, nothing is fetched, omitted means links stay relative), and mode with per-value rationale for auto/article/full. This adds meaning well beyond the bare enum and defaults in the 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?

"Convert HTML you already hold into clean Markdown, without fetching it" states a specific verb (convert), input (HTML in hand), and output (Markdown), and explicitly distinguishes itself from the sibling fetch_clean_markdown by the input source.

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?

Gives an explicit when-to-use trigger (HTML from a login-walled page, a file, or a previous fetch) and an explicit when-not-to-use with the named alternative ("If you have only a URL, use fetch_clean_markdown instead"). It also routes between modes: 'auto' unless the page shape is known, 'article' for news/blog, 'full' for table/list-heavy pages.

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