list_known_rails

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

With no annotations, the description carries full burden and effectively discloses behavior: it separates rails into native-settle and handoff categories, includes rails it doesn't move funds on, and implies the output is a catalog. This adds significant behavioral context.

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 purpose and provides structured detail into two modes and a pairing suggestion. While slightly long, every sentence adds value and avoids redundancy.

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 annotations, no output schema, and zero parameters, the description adequately covers the tool's purpose, output categorization, and relationship to siblings. It provides enough context for an agent to decide when to use 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 input schema has zero parameters, and the baseline for 0 parameters is 4. The description clearly explains the tool's function without needing parameter-level details, adding no redundancy.

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 explicitly states the action ('List') and the resource ('every agent-payment rail/protocol Interline knows about'), and distinguishes its purpose from the sibling tool 'discover_payment_rails' by noting they pair together for different needs.

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 explains when to use this tool ('one call = the whole agent-payment landscape') and how it relates to a sibling tool ('Pair with discover_payment_rails'), providing clear context though not explicit exclusions.

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