get_variable

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

readOnlyHint=true already tells the agent this is a safe read, and the description adds real value on top by disclosing the shape of the returned record (attributes, role, codelist refs under refs). It does not mention failure behavior for unknown variables/datasets, but for a read-only lookup that is a minor omission.

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?

Three short lines: what it returns, the scope restriction plus alternative tool, then a concrete example. The scope restriction and the redirect are front-loaded, and no sentence is filler.

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 correctly compensates by listing the returned fields, and the example demonstrates a valid invocation across all four required parameters. Remaining gaps are small: it does not say what happens when a variable name is not found, nor how the raw flag changes the returned payload beyond the schema's own note.

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 schema already carries the meaning of all five parameters, including the raw toggle and the 'latest' version sentinel – the description adds nothing to those. The worked example does reinforce value formats ('3-4', uppercase DM/USUBJID), which is a marginal gain over a fully documented schema and lands at baseline.

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 specific verb+resource ('获取指定变量的详细信息') and enumerates the payload an agent will get back: data type, core attributes (Req/Exp/Perm), role, and CT codelist references in refs. It also explicitly marks the boundary against the sibling 'get_datastructure_variable', so the tool is distinguishable without opening either 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?

It states the applicable standards (SDTM/SEND/CDASH) and names the alternative tool for ADaM variables, which is exactly the routing decision an agent needs. However, the input schema's enum still accepts 'adam'/'adamig', creating a residual ambiguity the description does not reconcile (e.g. whether those values error or are silently resolved).

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