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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the safe read-only nature is covered. The description adds value by indicating the returned data is 'live' and scoped to 'Relay-supported' sources routing into Base USDC, which is useful behavioral context beyond the annotations. No contradictions.

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 a single, concise sentence that is front-loaded with the core purpose ('Return live Relay-supported...'). Every word contributes meaning—no filler or redundancy. It is appropriately sized for a simple discovery tool.

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?

For a zero-parameter, no-output-schema tool, the description conveys the essential information: what is returned (source chains and tokens) and the condition ('before a Peer Cash order'). It does not specify the exact output format, but given the simplicity and that annotations cover safety, it is sufficiently complete for an agent to understand when and how to invoke 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?

The tool has zero parameters, so there is nothing to describe beyond the schema, which is empty. Per the calibration guidance, a baseline of 4 is appropriate when there are no parameters. The description does not need to elaborate on parameter meaning, since none exist.

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 a specific action ('Return') and a specific resource ('live Relay-supported EVM source chains and tokens that can route into Base USDC'). It is distinct from siblings like peer_cash_capabilities (broader) and peer_cash_quote_source (likely about quotes) by focusing on source assets for a Peer Cash order. The purpose is unambiguous and well-scoped.

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 says 'before a Peer Cash order', providing clear timing context. However, it does not mention any alternative tools (e.g., peer_cash_quote_source or peer_cash_capabilities) or specify when NOT to use this tool. The guidance is adequate but lacks exclusions or alternative routing, which would help an agent choose among the many peer_cash_* siblings.

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