validate_routing

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

Discloses both what the tool does (9-digit weighted mod-10 checksum) and its limitation (does not check if bank or account is real), which is critical for proper use.

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?

Two concise sentences with no filler, front-loaded with usage instruction.

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 simple validation tool with one parameter and no output schema, the description covers purpose, what it checks, what it doesn't, and usage context.

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 already documents the routing parameter as 'The 9-digit ABA routing number.' The description adds no extra semantic meaning beyond reaffirming the 9-digit format and referencing the checksum, which is behavioral context.

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?

Description clearly states the tool verifies a US bank routing/ABA transit number using a checksum, distinguishing it from sibling validation tools targeting other entities (e.g., email, card, IBAN).

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?

Begins with 'USE THIS to verify...' explicitly stating when to use it, but does not mention alternatives or when not to use among the many sibling validation tools.

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