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

Annotations already cover read-only and open-world behavior. The description adds valuable context beyond annotations: the data source is bundled public excerpts and access costs $0.005 via x402 payment, which is useful operational information. It does not say what happens on invalid codes or rate limits, keeping it from a 5.

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 tight sentences: the first front-loads what is looked up and from where, the second covers pricing and payment. Every sentence earns its place with no repetition.

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 read-only lookup with 100% schema coverage and annotations covering safety, the description is nearly sufficient. It could go further in describing the return shape (e.g., whether codes are mapped to descriptions) since no output schema exists, but the core operational context is present.

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 schema fully documents the three parameters and aliases. The description adds no parameter-level detail beyond the code types already implied. Baseline 3 is appropriate when the schema does the heavy lifting.

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 ('Look up') and specific resources (CPT/HCPCS/ICD-10 and CARC/RARC codes) plus the data source (bundled public CDC/CMS/X12 excerpts). No sibling tool overlaps this domain, so an agent can identify its purpose immediately.

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?

Usage is implied by the lookup purpose, but no explicit when-to-use or when-not-to-use guidance is given, and there are no alternatives to contrast with. The payment note is informative but does not clarify selection conditions.

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