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

Even with readOnlyHint=true and destructiveHint=false annotations, the description adds valuable behavior context: it returns matches sorted by most recently updated, includes a direct study URL, and discloses the cost per call ($0.02) and settlement method. This goes beyond annotation basics.

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?

Two information-dense sentences, perfectly front-loaded with the core purpose and quickly conveying output, source, cost, and access requirements. No wasted words.

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 that there is no output schema, the description compensates by listing the exact returned fields and the sort order. It covers tool purpose, data source, legal/access constraints, and cost, making it a self-contained explanation for an agent.

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%, so the baseline is 3. The description does not add extra parameter meaning beyond what the schema already provides; it only mentions output fields and sorting, which are not parameter-specific.

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 watches conditions, drugs, or sponsors for clinical trials and returns specific fields (NCT id, status, phase, sponsor, URL). It distinguishes from sibling tools by focusing on clinical trials and citing the official ClinicalTrials.gov API v2.

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?

Provides clear context for usage: it monitors new and updated trials via the official API, is free, and requires no API key or login. It does not explicitly name alternatives or exclusion criteria, but the domain specificity and 'official' designation imply when this tool is appropriate.

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