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

With no annotations provided, the description fully carries behavioral disclosure. It reveals the deterministic alphabetical ordering, the lack of provider endorsement, and most importantly warns about the gas purchase requirement and the two-purchase cold-start scenario. This is exceptionally transparent and prevents critical user errors.

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?

The description is dense but well-organized, with each sentence serving a purpose: function, filtering, use case, and the crucial gas warning. The 'IMPORTANT' section is clearly separated, and the return structure is outlined. No extra fluff.

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?

Given no output schema, the description outlines the top-level return fields ('providers, gas_requirement, filter_echo, notes') and highlights the gas_requirement field's significance. For a simple read-only catalog with optional parameters, this is sufficient, though it doesn't detail every nested field.

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?

The schema covers all parameters with descriptions, but the tool description adds meaning beyond the schema by explaining that parameters work together to 'narrow the catalog to providers that operate in the user’s jurisdiction and accept their transaction size.' This contextualizes the parameters beyond their individual schema text.

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 clearly states the tool's function: 'Returns a catalog of fiat-to-USDC onramps that deliver native USDC on the requested chain.' It adds specificity with the note about alphabetical listing and non-endorsement, distinguishing it from any potential alternatives and making its purpose unambiguous.

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?

It provides a concrete use case ('an LLM agent helping a novice user fund their wallet'), explains filtering by country and amount, and points to when this tool is needed. It does not explicitly mention alternatives or exclude other tools, but given the sibling set contains no other onramp-catalog tool, the guidance is adequate.

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