groupby

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

No annotations are present, so the description carries the full burden. It mentions accepting an Array but does not disclose how grouping is performed, whether grouping is by key, value, or custom logic, or what the return structure looks like. The truncated 'Returns a' fails to clarify behavior.

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?

The text is short and front-loaded, but the description ends abruptly mid-sentence ('Returns a "'), making it structurally incomplete. While brevity is good, the truncation prevents it from being a clean, self-contained description.

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 and no annotations, the description must explain return values and grouping behavior. It begins to do so but cuts off, leaving the tool functionally underspecified even for a low-complexity operation.

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?

The input schema has zero parameters and 100% coverage, so the baseline is 4. The description adds the key context that the tool accepts an Array of any data type, which complements the empty schema. No parameter documentation is needed since none exist.

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 identifies a specific verb 'Group' and resource 'an Array of items', which distinguishes it from peers that sort, filter, or transform arrays. However, the description is cut off mid-sentence ('Returns a "'), leaving the output semantics unclear and limiting full differentiation.

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?

No guidance is provided about when to use this tool versus alternatives like 'sort', 'filter', or 'sortbyproperty'. The description does not mention any exclusions, prerequisites, or context where grouping is preferred.

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