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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds useful behavioral context beyond those: rates are 'current', the tool implements a specific IRS revenue procedure, it classifies locations into High-Cost or Low-Cost, and it lists pricing/delivery details ('Premium API', '$0.25 USDC via x402'). No contradictions with annotations.

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?

Three concise sentences deliver purpose, regulatory basis, output categories, and cost without redundancy. The most important information is front-loaded, and every sentence adds value beyond the schema or annotations.

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 single-parameter lookup tool with no output schema, the description sufficiently explains what the agent will get back (classification, lodging rate, M&IE rate), the supported input scope, and the pricing model. Nothing essential is missing for correct invocation.

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 the parameter is already fully documented with an example and a clear description. The tool description adds no new parameter-level detail, which is acceptable given the high schema coverage; the baseline of 3 applies.

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 names a specific verb ('Retrieve'), a precise resource ('IRS high-low method per diem rates'), and a geographic scope ('any US location'). It also includes distinctive output details (High-Cost/Low-Cost classification, lodging and M&IE components) that separate it from the many other Interzoid data-lookup siblings.

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 clearly frames when the tool is relevant: 'to support accountable-plan travel reimbursement (Revenue Procedure 2019-48)'. It does not name alternatives or state when-not-to-use, but no sibling tool appears to provide per diem rates, and the use case is specific enough to guide selection.

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