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

Goes well beyond the readOnly/openWorld annotations: it discloses the sanitization steps (hidden text, invisible characters, exfiltration links stripped), that a prompt-injection risk report is included, that robots.txt is honored, and — critically — the exact cost (US$0.005 USDC on Base via x402) with the no-charge-on-failure guarantee. That payment and billing behavior is unavailable anywhere in the structured fields.

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 clauses, each load-bearing: capability and return shape first, then safety/sanitization behavior, then cost. No filler or restatement of the tool name.

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 carries the return-value burden and does so (markdown plus risk report). It also covers billing and robots.txt, leaving only minor gaps such as failure modes or what the risk report contains.

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 100%, so the baseline is 3. The description only adds the 'public page or PDF' scope for the url parameter and never mentions the format enum (markdown vs. text), so it contributes little beyond what the schema already documents.

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?

Names a specific verb+resource pair (fetch a public web page or PDF) and states the returned artifact (clean markdown plus a prompt-injection risk report), which no sibling tool (scan_content, audit_mcp_server, audit_skill) does. An agent can tell exactly what this produces 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?

The word 'public' plus 'respects robots.txt' sets a clear precondition, and the sanitization framing implies it is the right choice when the content will be passed to a model. It never names an alternative or states when not to use it (e.g. vs. scan_content for untrusted local content), so it stops short of explicit routing.

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