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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds useful return-content context — observed changes and data freshness — but says nothing about pagination behavior for locations or how much of the record can be truncated.

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 dense sentence that front-loads the identifier-based lookup and then lists returned fields; there is little waste. The trailing clause about observed changes and freshness makes it slightly run-on but still readable.

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?

With no output schema, the description does a fair job describing the returned record's shape. However, for a tool with a nested object parameter and zero schema descriptions, the description is silent on filtering/limiting semantics, and the overlap with get_trial_changes is left unexplained.

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 0% across three parameters, including a nested location_filter object with city/state/country and a max_locations cap. The description only hints at nct_id ('by NCT id') and leaves the location-filtering parameters entirely undocumented, so it fails to compensate for the coverage gap.

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 names a precise verb and resource — retrieving one study by NCT id — and enumerates the record's contents (status, dates, enrollment, eligibility, sites, contacts, outcomes, documents). 'One study by NCT id' clearly separates it from the search_* siblings, though no sibling is named explicitly.

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?

Usage is only implied: the agent must already hold an NCT id, which the description states but never turns into a when-to-use rule. It also mentions 'the changes AgentStructure has observed' without telling the agent how this differs from the get_trial_changes sibling, leaving a real routing ambiguity unresolved.

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