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

Goes well beyond the readOnly/openWorld annotations: discloses per-call cost ($0.025, $0.0025 each), the x402 payment mechanism via _meta['x402/payment'], USDC on Base, and the exact return shape. This is rich behavioral context an agent needs before spending money.

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?

Front-loads the batch purpose and size cap, then price and format. Dense but each sentence adds distinct value; the inline example output is somewhat verbose but substitutes for a missing output schema.

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 supplies an example return payload and summarizes the pay/caution/avoid counts, plus pricing and payment transport. An agent has everything needed to invoke and interpret it correctly.

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 both params are documented. The description adds the JSON-body alternative format for urls, but says nothing about maxPrice semantics — a baseline 3 is appropriate since the schema carries the load.

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+scope: 'Batch x402 precheck: up to 10 URLs in one call' and names the underlying check (hearth.precheck.v2). The 'batch' framing clearly separates it from the sibling x402_precheck single-URL tool.

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?

Clear usage context: use when checking multiple URLs at once, with the 10-URL cap stated as a hard limit. It does not explicitly say 'use x402_precheck for a single URL', so the routing to the sibling is left to inference from the name.

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