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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the safety profile is covered. The description adds context by specifying the metric (total count) and data source, and includes a freshness reference (577,000+ as of March 2026). This supplements the annotations with useful behavioral details, though it omits the 'average record size' noted in the schema parameter description.

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?

A single concise sentence provides the essential information: the tool returns a total count from a specific source with a current figure. No redundancy or extraneous details; optimally front-loaded.

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?

The description is sufficient for a no-parameter statistics endpoint. It explains the core purpose and data source, and an output schema exists to describe the return format. The only minor gap is that it does not mention the average record size also returned, but this is captured in the schema parameter description.

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%, with the single 'dummy' parameter fully documented as unused. The tool description itself adds no parameter semantics, so it relies entirely on the schema. Baseline 3 is appropriate since the schema carries the full burden and the parameter is trivial.

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 reports the total number of registered clinical studies in ClinicalTrials.gov, with a specific metric and source. It distinguishes from sibling tools like health.clinical.search and health.clinical.study, which handle searching and individual study details, by focusing on an aggregate statistic.

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 provides no guidance on when to use this tool versus alternatives such as health.clinical.search or clinicaltrials.trials.stats. There is no mention of exclusions or preferred use cases, leaving the agent to infer applicability.

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