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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, and the description goes well beyond them: it documents the JSON return fields, hard caps (200KB, 8s, 3 redirects), the private/localhost block, that errors are not charged, the x402/USDC-on-Base pricing, and an explicit prompt-injection warning about untrusted returned content. That is exactly the extra context the annotations cannot carry.

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?

Dense but front-loaded: the core purpose and trigger come first, then return shape, then operational limits, then security and payment caveats. Every sentence carries distinct, actionable information with no filler.

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?

No output schema exists, but the description enumerates the returned fields (content, format, finalUrl, upstreamStatus, contentType, bytesRead, truncated) as well as limits, error behavior, and payment terms. Nothing an agent needs to invoke or interpret the call is missing.

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% on a single param, so the baseline is 3. The description adds real constraint detail the schema does not: the URL must be absolute http/https, private/localhost targets are rejected, and it is required — enough to edge above baseline.

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+resource ('URL to markdown scraper') and frames the outcome ('read a public web page as clean text or markdown for an LLM'), which implicitly separates it from a raw HTTP sibling and from screenshot/pdf extractors. An agent can tell what this returns 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?

Gives a clear context trigger ('use when you need to read a public web page as clean text or markdown for an LLM') and a hard exclusion (private and localhost targets are blocked). It does not, however, name an alternative sibling (e.g. http, extract, search) or state when not to use it, so routing is left partly to inference.

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