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

Annotations already establish the safe read-only, idempotent, open-world profile, so the bar is lower. The description still adds real behavior beyond the schema: a result cap ('up to eight matching codes') and the shape of returned Medicare data ('typical allowed and billed amounts').

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?

Front-loaded with purpose, then usage framing, then return shape. The three examples are slightly redundant with the stated trigger but each maps to a distinct query type, so little is wasted.

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 two-param, read-only lookup with no output schema, the description supplies purpose, trigger, examples, and the return shape, and the state example signals locality-dependent rates. Nothing an agent needs to call it correctly is missing.

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 q and state are already documented in-schema; baseline is 3. The description reinforces that q accepts either plain words or a raw code and that state drives the rate shown (the Ohio example implies locality), but adds no format or syntax detail the schema lacks.

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 (find) and resource (billing codes and Medicare rates) with the discriminating input style (plain words). It is clear what the tool does, but it never names or contrasts with the sibling medbillcheck_check_price, leaving the boundary between 'search services' and 'check price' to be inferred.

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 gives explicit trigger conditions — 'someone describes a service but has no code, or asks what a code means' — plus three concrete query examples spanning code lookup, price lookup, and code explanation. It stops short of stating when NOT to use it or pointing to the sibling alternatives.

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