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

Annotations already declare read-only, idempotent, open-world behavior, but the description adds meaningful context: it 'Reads the live CPSC lab list' (freshness/source) and explicitly disclaims booking and pricing. The negative capability statements are the strongest value-add; it stops short of noting rate limits or result volatility.

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 inputs, then return shape, then negative scope. Every sentence earns its place except the return-field enumeration, which partially duplicates the existing output schema.

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?

Because an output schema exists, the description need not explain returns in depth, and annotations cover the safety profile. The description is complete enough for an agent to chain from find_cert_rules to this tool across countries and toy/metal variants.

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 coverage is 100%, so the structured fields already document each parameter well. The description still adds workflow meaning by tying ruleIds to find_cert_rules output and explaining that metalParts forces an additional lead-in-metal test, which is more than the schema's field-level text conveys.

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 with scope: 'Shortlist testing labs that CPSC currently accepts for every test a product needs, in one country.' It is clearly distinguished from the adjacent find_cert_rules (upstream input source) and from check_lab_report.

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?

Explicit routing: 'Pass ruleIds from find_cert_rules (testedRuleIds), and country if the user names one,' plus conditional guidance for toys (f963Sections) and metal products (metalParts). It also states when NOT to use it: 'It does not book a lab or quote prices.'

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