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

Goes well beyond the annotations (readOnlyHint=false, idempotentHint=true) by disclosing the exact cost (0.25 USDC on Base or Solana), the return encoding (gzip+base64 JSON plus digest), the 60-second signed download URL for large results, and the 30-day result-recovery behavior. The 'Never signs payments' clause usefully clarifies that the caller must supply proof, and it is consistent with the idempotentHint.

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?

Four dense sentences, front-loaded with scope and result format, then payment cost, then recovery semantics. No filler; each sentence adds operational information.

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, yet the description fully covers the return shape (gzip+base64 JSON, digest, signed URL), payment/auth requirements, idempotency-based recovery, and the truncation cap. An agent has everything needed to call and interpret 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 0%, so the description must carry the parameter burden. 'Reuse the original body and payment proof for exact 30 day result recovery' gives real meaning to idempotency_key and payment_signature, but it never explains the key format, length constraints, or the distinction between the two parameters, leaving gaps the schema cannot fill.

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 (export) and resource (visible scanned x402 services), and enumerates exactly what is included: grade history, first seen, scan counts, provenance and explicit truncation. This clearly separates it from siblings like search_listings and retrieve_listing, which are retrieval rather than bulk export.

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 description implies the usage context (bulk export up to 10000 records, truncation handling, paid operation) but never explicitly states when to choose this over search_listings or retrieve_listing, nor any prerequisites beyond payment. Usage is inferable but not routed.

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