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

Annotations already cover read-only and idempotency, yet the description still adds real behavioral detail: per-event error entries instead of whole-call failure, no protocol errors ever raised, a structured {"error": ...} shape, and retry safety after correction. It also notes the 30-event cap is silently applied, which is important since excess input is dropped rather than rejected.

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?

Purpose and sorting rule are front-loaded, then usage, then error and retry semantics — a sensible ordering. The "FREE." line is marketing noise and the inline example output is somewhat padded, but the sentences otherwise carry information.

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-param, nested-object tool with an output schema and full annotation coverage, this description covers purpose, alternatives, error mode, retry safety, and input shape. Nothing an agent needs to invoke it correctly or recover from failure is missing.

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 baseline is 3, but the description earns extra credit by showing a concrete input payload and by disclosing that a malformed date degrades to a per-event error rather than invalidating the mapping. That error-granularity detail is a semantic the schema does not convey.

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?

"Count the days until each named event, soonest first" gives a specific verb, resource, and output ordering in one clause. It also explicitly disambiguates from two named siblings (business_days, spaced_repetition_plan), so an agent can pick it without opening the schema.

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?

"Use to rank named dates by how soon they arrive" states the selecting condition, and the following sentence names both alternatives with the conditions that route away from this tool. Explicit when-to-use and when-not-to-use are both present.

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