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

Annotations already declare readOnly, idempotent, non-destructive, open-world behavior, and the description adds real value beyond them: the tool is free, pricing is quoted in USDC on Base or Solana, and each entry exposes path, price, return payload and parameters. It does not cover pagination or catalog size, which keeps it from a 5.

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 tight sentences, front-loaded with the cost/scope fact, then the returned fields, then the follow-up pointer and optional filter. No sentence is redundant or padded.

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?

There is no output schema, so describing the shape of each returned entry (id, path, price, payload, parameters) is exactly the missing information an agent needs, and the linkage to call_endpoint closes the loop. For a one-parameter read-only catalog tool this is complete.

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% and the single free_only parameter is already documented in the schema; the description's 'keeps only resources that cost nothing' merely restates it. Baseline 3 applies since the schema does the heavy lifting for the only parameter.

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 (lists) and resource (every resource Blockchain IQ sells per call over x402), and enumerates the returned fields (id, path, price, what it returns, parameters). An agent can immediately distinguish this catalog-listing tool from call_endpoint.

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?

Explicitly says to take the id and use it with call_endpoint, so the follow-up action is unambiguous, and it explains the free_only filter's effect. It does not state a when-not condition (e.g., that this returns no payload data itself), so it stops short of full alternative/exclusion guidance.

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