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

Annotations already declare readOnlyHint=true, idempotentHint=true, and openWorldHint=false, covering safety and non-mutating behavior. The description adds behavioral context by specifying the required input format and the list of return fields, going beyond what annotations provide. No contradictions.

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 three sentences, front-loaded with purpose and returns, then requirements, then related tools. No fluff; every sentence adds value.

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 single-parameter, read-only lookup tool with strong annotations and no output schema, the description adequately covers purpose, input requirements, return values, and alternatives. It is complete for the tool's complexity.

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?

The input schema provides a basic description for product_code ('Device product code') with 100% coverage, but the tool description enriches this with the specific 3-letter code format and its sources (510(k), PMA, device product listings), aiding the agent in constructing valid input.

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 tool's function with a specific verb ('Lookup'), the resource ('FDA device classification details'), and the method ('by product code'). It lists the specific data returned and distinguishes itself from related sibling tools (fda_product_code_lookup, fda_search_510k, fda_search_pma).

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 explicitly states the prerequisite (product code from 510(k), PMA, or device product listings) and names three alternative tools with their distinct purposes, effectively telling the agent when to use this tool versus alternatives.

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