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

Annotations only carry openWorldHint=true and readOnlyHint=false; the description adds substantial behavioral context: the 0.01 USDC x402 cost, the two-phase flow ('Without payment_signature returns payment instructions'), and the security directive to sign locally and never submit a private key. This meaningfully exceeds the structured fields and explains why readOnlyHint=false despite being a fetch.

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 with zero filler: purpose and cost in sentence one, conditional flow in sentence two, security constraint in sentence three. The most important operational facts (cost, payment requirement, key safety) are front-loaded ahead of any optional detail.

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?

The payment flow and security posture are covered, and the mode field's schema description hints at the output shape (provenance, passages). However, with no output schema present, the description never states what the default 'full' response contains, what error conditions look like, or what happens after a valid payment_signature is supplied. A paid tool with a two-phase handshake warrants a bit more coverage.

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 80%, so the schema already documents url, mode, query, and payment_signature. The description adds value by explaining the conditional role of payment_signature — that omitting it triggers a payment-instructions response rather than the fetched content. This is semantic information the schema's field description ('Base64 x402 PAYMENT-SIGNATURE produced by your wallet adapter') does not convey.

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 and resource: 'Fetch public static web context.' The word 'context' (rather than raw HTML) plus the mode field's mention of provenance and passages implies a processed result, which distinguishes it from the sibling extract_html. However, it never explicitly names the sibling or states the boundary, so an agent must infer the difference.

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?

No guidance on when to choose this tool over extract_html or example. The description explains the payment flow but not the selection criteria — e.g., when static context suffices versus when raw HTML extraction is needed. The agent is left to infer usage from the schema and name alone.

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