List supported chains, their tokens and DEX venues

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

With no annotations provided, the description carries the behavioral disclosure burden. It transparently explains the authentication-dependent behavior: with a RapidAPI key the full token/venue lists are returned, while without one a public snapshot is used that omits token universes. It also mentions the paid route and free tier availability, adding valuable context beyond the tool's basic operation.

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 front-loaded with the main action and scope, followed by operational details. Every sentence adds meaningful information—output contents, usage ordering, authentication behavior, and key source—with no redundancy. It is appropriately sized for the tool's complexity.

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 there is no output schema, the description thoroughly explains what the response will include: chains, chain IDs, native assets, pairs, tokens, and DEX venue types. It also covers auth variants, prerequisites, and usage context, making the tool fully understandable without structured output documentation.

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 tool has zero parameters, so the schema fully covers the input side. The description compensates by explaining what data the response will contain, which is more than enough for a parameterless tool. No additional parameter semantics are needed.

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 identifies the tool's purpose: listing all supported blockchains with chain IDs, native assets, default trading pairs, token tickers, and DEX venues. It uses a specific verb ('List every blockchain') and enumerates the exact scope, distinguishing it well from sibling tools like get_pairs or get_prices.

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 explicitly instructs 'Call this first to discover valid chain values for the other tools,' providing clear usage context and positioning it as a prerequisite. However, it does not explicitly state when not to use it or compare it to alternatives, so it stops short of a 5.

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