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

With no annotations, the description carries the full burden. It does add genuine behavioral context not in the schema: no network fetch is performed, the specific return payload, and a paid cost model ($0.001 USDC on Base via x402). However, it omits error behavior, size-limit implications (the 500k char cap), and whether malformed HTML is tolerated.

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?

Three sentences, each earning its place: the first states purpose and the key non-fetching constraint, the second enumerates return values, the third discloses cost. Front-loaded and waste-free.

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 two-parameter tool with no output schema, the description supplies the return field list and the non-obvious cost model, which is strong. The remaining gap is the undocumented base_url parameter, which an agent cannot infer from the schema alone.

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% for two parameters, so the description should compensate. It addresses 'html' implicitly ('caller-supplied raw HTML') but never explains what 'base_url' is for or when it should be supplied – likely to resolve relative canonical/URL references. That half of the parameter surface is undocumented everywhere.

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 (parse) and resource (metadata from raw HTML) and explicitly distinguishes itself from sibling fetch-based tools: 'without fetching a webpage URL'. It even enumerates the returned fields (title, canonical URL, meta tags, JSON-LD), so an agent can tell it apart from extractWebpageMetadata without opening either 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?

Clearly frames the use case: 'caller-supplied raw HTML' for 'local HTML-processing workflows', implicitly routing agents that already hold HTML here and URL-fetching agents elsewhere. It stops short of naming the alternative tool explicitly or stating exclusions (e.g., malformed HTML handling).

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