cdc_life_expectancy

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds the temporal limitation (data goes through 2018) which is not in annotations and is critical for correct usage. It also points to an alternative for more recent data. It doesn't describe return format, but for a read-only data retrieval tool with no output schema, that is a minor gap.

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, with the core purpose in the first sentence, valid values in the second, and a usage note in the third. It is front-loaded and contains no filler. Every sentence adds value, and the key scoping constraint (date range) is stated early.

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?

Given no output schema, the description implies the result (life expectancy values) but doesn't specify structure. However, the tool is simple and the parameters are well-documented. Annotations cover safety and idempotency. The only missing piece is a note about pagination or response format, but the 'limit' parameter hints at pagination. Overall, sufficient for an agent to call correctly without extra context.

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% – all four parameters have descriptions. The description repeats the enum values for sex and race, but that adds no new meaning beyond the schema. The year range is already in the schema description. The 'limit' parameter is covered by schema. No additional semantic insight is provided beyond what the schema already offers, so baseline 3 is 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?

The description states a specific verb ('Get') with a clear resource ('U.S. life expectancy at birth') and scope (by race and sex, 1900–2018). It also lists the exact allowed values for race and sex, which differentiates it from other CDC tools. The final sentence explicitly names the sibling cdc_mortality_rates as the alternative for more recent data, distinguishing it.

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 clearly indicates when to use this tool: when the user needs life expectancy data within the 1900–2018 range. It also explicitly says 'For more recent mortality trends, use cdc_mortality_rates,' giving an alternative and the condition to choose it. This is direct and actionable.

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