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

Annotations already provide readOnlyHint=true. The description adds value by specifying the services checked (ACH, Real-Time Payments, wire). However, it fails to mention that the query supports pagination (limit, cursor) as indicated in the schema. This omission could lead to incomplete understanding of the tool's behavior.

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: first explains what the tool does, second provides the underlying API endpoint. No extraneous information. Front-loaded with key purpose.

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?

With no output schema, the description should clarify the return structure (e.g., a list of supported services). It mentions the services but not the format. Additionally, pagination is hinted only in the schema, leaving the AI to infer response shape. Completeness is adequate but not robust.

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 description coverage is 100%, so each parameter is already described. The tool description adds no additional parameter-specific details beyond the overall purpose. It does not explain how limit and cursor affect the lookup or that the response may be paginated.

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 verb 'look up', the resource '9-digit ABA routing number', and the outcome 'see which real-time services (ACH, Real-Time Payments, wire) that bank supports'. It uniquely identifies the tool's purpose and distinguishes it from sibling tools which deal with accounts, transfers, etc.

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 does not explicitly state when to use this tool versus alternatives. However, because no sibling tool performs a routing number lookup, the usage context is implied. The description could be improved by adding a note like 'Use this when you need to check a bank's real-time service capabilities.'

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