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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world behavior. The description adds valuable return behavior beyond the annotations: 'Returns up to eight matching codes with Medicare's typical allowed and billed amounts.' This return limit and content are useful and not present in structured fields.

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 core purpose, then usage context, examples, and return behavior. Every sentence earns its place, though the opening 'Med Bill Check.' is redundant with the title and could be trimmed.

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 correctly provides return value information ('up to eight matching codes with Medicare's typical allowed and billed amounts'). It covers the required parameter through examples and relies on the schema for optional parameters. A minor gap is the lack of explanation for the optional state parameter interaction.

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 both parameters are already documented. The examples illustrate that 'q' can accept plain words or a numeric code, adding some meaning, but the description does not clarify how the separate 'state' parameter should be used versus embedding a state in the query. Baseline 3 is appropriate.

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?

States a specific verb and resource: 'Find billing codes and Medicare rates by plain words.' It distinguishes itself from siblings by specifying the use case 'when someone describes a service but has no code, or asks what a code means,' which separates it from a code-based price lookup like check_price.

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?

Gives clear when-to-use guidance with three concrete examples covering description-to-code, rate lookup, and code-to-meaning queries. However, it does not name alternative sibling tools or state when *not* to use this tool, so it falls short of the explicit exclusions/alternatives bar for a 5.

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