code_lookup

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

With no annotations provided, the description carries full burden. It discloses the return data (description, category, active status, related codes) which is valuable behavioral information. However, it doesn't mention error handling, rate limits, authentication needs, or whether this is a read-only operation (though 'look up' implies it).

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 perfectly concise - two sentences with zero waste. The first sentence states purpose and parameters, the second describes return values. Every word earns its place and it's front-loaded with the core functionality.

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 lookup tool with no output schema, the description provides good coverage of what it does and what it returns. However, without annotations and with no output schema, it could benefit from more behavioral context about error cases or limitations. The description compensates well but isn't fully complete.

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 already fully documents both parameters. The description doesn't add any parameter-specific information beyond what's in the schema descriptions. This meets the baseline of 3 when 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 clearly states the specific action ('look up'), resource ('medical codes'), and scope (ICD-10, CPT, HCPCS). It distinguishes from siblings like code_crossref, code_suggest, and code_validate by focusing on direct lookup rather than cross-referencing, suggestion, or validation.

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 implies usage for retrieving code details, but doesn't explicitly state when to use this versus alternatives like code_crossref or code_suggest. It provides clear context for code lookup scenarios but lacks explicit exclusions or comparisons with sibling tools.

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