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

Annotations only cover safety (readOnly, openWorld, not destructive); the description adds substantial operational context beyond them: the exact return payload (risk report plus cleaned text wrapped as untrusted data), a hard size ceiling of 256 KB, and a paid-call requirement of US$0.002 in USDC on Base via x402. Payment and size constraints are exactly the kind of hidden behavior an agent must know before invoking.

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 short sentences: what it scans, what it returns, then cost and size limit. Each sentence carries distinct information and the most decision-relevant constraint (only scan content you already have) is front-loaded.

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 output schema, the description takes on the burden of describing the return value and does so (risk report plus cleaned text marked untrusted). Combined with the payment and size disclosures, an agent has everything needed to decide and correctly invoke it.

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 75%, so most parameters are already documented in the schema. The description reinforces the content parameter's accepted types and adds a 256 KB limit, but says nothing about the optional url provenance field, the html/text format enum, or the return_text toggle. Baseline 3 applies.

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?

The description states a specific verb (scan) and resource (HTML or text) and scopes it to content the agent already holds, which implicitly sets it apart from the fetching sibling read_url. An agent can tell what this does 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?

Parenthetical examples (an email, a document, a tool result) and the phrase 'you already have' give clear context on when this applies, implying read_url should be used first to obtain content. It never names the alternative explicitly or states when not to use it, so it stops 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.