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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description adds genuinely useful behavior beyond that: a result cap ('up to eight matching codes') and the fields returned ('Medicare's typical allowed and billed amounts'), which helps the agent set expectations about coverage.

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 purpose followed by usage conditions and examples; every sentence serves selection or expectation-setting. The three inline examples are slightly verbose but each maps to a distinct usage mode, so the space is largely earned.

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 present, the description carries the return-value burden and does so: it states the result cap and the money fields returned. Combined with full param coverage and clear usage triggers, an agent has everything needed to call it correctly.

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 with examples. The description implicitly references state-scoped pricing ('in Ohio') but adds no syntax or format detail beyond what the schema already supplies, making the baseline 3 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+resource ('find billing codes and Medicare rates') and clarifies the input modality ('by plain words'). It cleanly separates the 'no code yet' and 'decode an existing code' cases, but does not differentiate itself from sibling check_price, which plausibly overlaps on pricing.

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 explicit trigger conditions ('when someone describes a service but has no code, or asks what a code means') plus three concrete query examples, so an agent knows exactly when to reach for it. It stops short of naming alternatives like check_price or look_up_hospital for the exclusion case.

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