Rectangular Array

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

The annotation readOnlyHint=false already indicates mutation, and the description reinforces that by saying 'Create.' It goes beyond annotations by disclosing the potentially large result set ('a 40x40 grid hands back 1600 full records') and the ability to control output via `fields`. This adds meaningful behavioral context about resource usage and return volume that the annotations alone do not convey.

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 description is two sentences, each earning its place. The first sentence states the core purpose, while the second delivers a critical performance warning and a practical tip. There is no filler or repetition of schema details, making it extremely efficient and well-structured.

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 the tool's complexity (7 parameters, output schema present, readOnlyHint annotation), the description covers the essential behavioral aspects: it identifies the creation nature, the return of all copies, and the risk of large results. The output schema handles return value details, so the description doesn't need to repeat those. A minor gap is the lack of explicit mention of spacing parameters, but the schema provides that. Overall, it is complete enough for an agent to invoke correctly.

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 already provides 100% coverage with descriptions for all parameters, so the baseline is 3. The description adds further meaning by highlighting that 'rows x cols is unbounded,' which warns about the multiplicative nature of these parameters and their impact on result size. It also recommends a specific value for `fields`, enriching the semantics of that parameter beyond the schema's generic description.

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 action: 'Create a rectangular array of copies.' It specifies the resource (rectangular array) and is distinct from siblings like entity_array_polar, which handles polar arrays. The verb 'Create' and the resource 'rectangular array' are precise and unambiguous.

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 practical usage guidance by noting the result-heavy nature ('rows x cols is unbounded') and recommending a minimal field projection ('fields=["handle"] is usually all a caller needs from it'). It does not explicitly name alternatives, but the tool's name and context imply when to use it (rectangular vs polar). This is a clear, useful guideline, falling just short of offering explicit when-not-to-use or alternative tool recommendations.

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